Paper: BEL Placement Paper (Technical- Electronics V)

  1. VSWR on a transmission line is always         1. Equal to 1         2. Equal to 0         3. Less than 1         4. Greater than 1   2. In a amplitude modulated wave, the value of Vmax is 10V and Vmin is 5V. The % modulation in this case is:         1. 2%            b. 33.3%             c. 50%              d. 100%   3. The signal to noise ratio at the input of an amplifier can be improved:         1. By decrease the source impedance or resistance         2. By increasing the source impedance         3. By matching the source impedance with the input impedance of the amplifier         4. None of these   4. If the bandwidth of an amplifier is reduced, the thermal noise in the amplifier will:         1. Increase         2. Decrease         3. Not to be affected at all         4. Become random in nature   5. For the distortion to be minimum in a transmission line at audio frequencies, the condition is         1. L = CR / G         2. L = GR / C         3. LG = R         4. LR = G   6. When electromagnetic waves are propagated in a waveguide         1. They travel along the broader walls of the waveguide         2. They travel through the dielectric without touching the wall         3. They are reflected from the walls but they do not travel along them         4. None of these   7. Communication between satellite and ground station is through         1. Tropospheric scatter         2. Ground wave         3. Sky wave         4. Line of sight propagation   8. A mast antenna is used mainly for         1. UHF         2. Short wave         3. Medium wave         4. VHF   9. A crystal which has a sensitivity of -55 dBm with 1 MHz  BW amplifier will have a sensitivity at 4 MHz BW amplifier equal to:         1. -55 dBm         b. -58 dBm        c. -52 dBm            d. -60 dBm  10. Electromagnetic waves are refracted when they         1. Pass into a medium of different dielectric constant         2. Are polarized at right angles to the direction of propagation         3. Encounter a perfectly conducting surface

         4. Pass through a small slot in a conducting medium  11. An aerial is fed from an amplitude modulation amplifier. Both the modulating voltage and modulated voltage are sinusoidal. The aerial current (rms) before modulation is 5 A and it increases to 5.8A after modulation. The percentage of modulation index will be         1. 88%         b. 80%         c. 81.21%            d. 83.14%  12. In a frequency demodulation, Foster-Seeley discriminator uses a         1. Single tuned circuit         2. Double tuned circuit in which both the primary and secondary are tuned to the same frequency         3. Double tuned circuit in which both the primary and secondary are tuned to to different frequencies         4. Combination of two transistors in push-pull operation  13. The wavelength of an electromagnetic wave in wave guide         1. Is directly proportional  to the phase velocity         2. Is inversely proportional  to the phase velocity         3. Is greater than that in free space         4. Depends only on the wave guide dimensions and the free space wavelength  14. The scale used for moving coil meter is         1. Non-linear scale         2. Linear scale         3. A square scale         4. A log scale  15. To double the circuit range of a 50 mA, 2000W meter movement, the shunt resistance requires is         1. 40W        b. 50W          c. 2000W             d. 25KW  16. A voltmeter utilizes a 20 mA meter movement. The sensitivity of the voltmeter is         1. 50 meg ohms per volt         2. 20 K ohms per volt         3. 50 kilo ohms per volt         4. 20 meg ohms per volt  17. A transformer, with a 20 : 1 voltage step-down ratio has 6V across 0.6 ohm in the secondary, then Is       and    Ip given by         1. 10A, 5A         2. 5A, 10A         3. 10A, 0.5A         4. 1A, 0.5A  18. The temperature coefficient of resistance of a resistor is         1. Negative         2. Positive         3. Zero         4. Infinity  19. To prevent loading of the circuit under test, the input impedance of the oscilloscope         1. Be low         2. Be high         3. Capacitive         4. Inductive  20. If the retrace is visible on the CRT display, then the trouble may be that         1. The fly back time of the time base saw tooth wave is not zero

         2. The blanking control is not set properly         3. There is loss of SYNC signal         4. The intensity is too high  21. The lissajous pattern on CRO for two sinusoidal of frequency ratio 1 : 2 differing in phase by 90 degrees, is         1. A straight line         2. A circle         3. An ellipse         4. An eight-shaped  22. When an electron starts from rest under the influence of electric and magnetic fields perpendicular to each other, the path traversed by it will be         1. Ellipse         2. A parabola         3. Straight line         4. A cycloid  23. Frequency multipliers are usually         1. Class A amplifiers         2. Class B amplifiers         3. Class C amplifiers         4. Class AB amplifiers  24. The feedback network of a phase shift oscillator is usually consists of         1. RC circuit         2. RL circuit         3. LC circuit         4. C alone  25. Common base amplifier is most suitable for use in         1. Very high frequency circuits         2. Low frequency circuits         3. Medium frequency circuits         4. Low current circuits  26. If two amplifiers having identical bandwidth are cascaded, then the bandwidth of the resulting amplifier will be         1. Less than that of each stage         2. Greater than that of each stage         3. Same as that of each stage         4. Double of each stage  27. Which one of the following amplifier has largest bandwidth         1. RC coupled amplifier         2. Difference amplifier         3. Transformer coupled amplifier         4. Direct coupled amplifier  28. In an amplifier, the emitter resistance by passed by a capacitor         1. Reduces the voltage gain         2. Increases the voltage gain         3. Causes thermal run away         4. None of these  29. The term free running is usually associated with         1. Bistable multivibrator

         2. Astable multivibrator         3. Monostable multivibrator         4. None of these  30. The signal fed at the input of an ideal push-pull amplifier has frequency components 150Hz'    300Hz,     450Hz and 600Hz. The output signal will contain         1. Only 150 Hz frequency component         2. Only 150 Hz and 450 Hz frequency component         3. Only 300 Hz and 600 Hz frequency components         4. All the frequency components  31. For which of the following configuration [s] does the input resistance of the amplifier depend strongly on the load resistance         1. CE       b.CC           c. CB            d. CE and CB  32. An important advantage of the RC coupling scheme is         1. Economy         2. Excellent frequency reponse         3. High efficiency         4. Good impedance matching  33. The AC input to transistor oscillator is obtained from         1. The previous stage         2. A signal generator         3. DC power source         4. Its own internal circuit  34. The low frequency cut-off in an amplifier is due to         1. Only coupling capacitor         2. Only bypass capacitor         3. Both coupling and bypass capacitors         4. The internal transistor junction capacitances  35. In a half-wave rectifier the peak value of AC voltage across the secondary of the transformer is 20/2 V. If no filter circuit is used, the maximum DC voltage across the load will be         1. 28.28V       b. 20V          c. 14.14V             d. None of these  36. Heat sinks ate used in a transistor working as power amplifier so as to         1. Increase the output power         2. Reduce the heat losses in toe transistors         3. Increase the voltage gain of the amplifier         4. Increase the collector dissipation rating of the transistors  37. In a power amplifier, the output power is proportional to         1. Vi         b. Vi2          c. Vi3            d. Ã- Vi  38. At half power frequencies the reduction in voltage gain of an amplifier equals         1. 6 dB          b. 2 dB           c. 3 dB         d. 4 dB  39. the frequency of the ripple voltage at the output of a bridge rectifier operating from a 50 Hz supply is         1. 25Hz          b. 50 Hz         c. 100 Hz           d. 200 Hz  40. Darlington pair is used for         1. High current gain         2. High power gain         3. High frequency operation         4. Low distortion

  41. The function of a bleeder resistor in a power supply is         1. Same as that of a load resistor         2. To ensure a minimum current drain in the circuit         3. To increase the output current         4. To increase the output DC voltage  42. A JFET has a potential divider bias arrangement. By mistake the resistor between the gap and the power supply terminal is removed. The JFET will         1.  Continue to work as an amplifier         2. Have a forward bias gate with respect to source         3. Not work as  an amplifier but will work as a switch         4. Immediately burn out  43. The ripple factor of half-wave rectifier is         1. 0.482          b. 1.11            c. 1.21             d. 1.57  44. In the high frequency region of an RC coupled amplifier the circuit behave like a         1. Differentiator         2. A current amplifier         3. Low pass filter         4. High pass filter  45. Astable multivibrator can be used as         1. Squaring circuit         2. Comparator circuit         3. Voltage to frequency converter         4. Frequency of voltage converter  46. If the gain of the amplifier as A and the voltage feed back is fraction B of the amplifier output voltage, the condition for maintenance of oscillation is         1. AB = 1 180o          2. AB = infinity         3. AB = 1  0o         4. AB  < < 1  47. Nominal gain of an amplifier is 240. The noise level in the output without feed back is 300 mV. If a feed back Beta = 1/ 60 used, the noise level in the output will be         1. 1.66 mV          b. 2.4mV             c. 4mV            d. 20mV  48. A zener diode is primarily used for         1. Rectification         2. Producing constant current         3. Producing constant voltage         4. Reverse bias  49. Cross over distortion is eliminated in a push-pull amplifier by         1. Using a transformer with a large step-up ratio         2. Using a transformer with a large step-down ratio         3. Providing a small forward bias to the transistors         4. Supplying both transistors with inphase signals  50. When a PNP transistor is saturated         1. Its base, emitter, and collector are all essentially at the same potential         2. Its emitter is at higher potential than the collector         3. Its collector is at higher potential than both base & emitter         4. None  51. For a RC high pass circuit

         1. RC < < t         2. RC > > t         3. RC = t         4. None  52. An inverter is an equipment for transforming         1. AC to DC         2. AC to AC         3. DC to DC         4. DC to AC  53. Suppose you wish to amplify the potential difference between two points in a circuit when neither of these points is grounded. Which one the following will you prefer?         1. RC coupled amplifier         2. Transformer coupled amplifier         3. Difference amplifier         4. Direct coupled amplifier  54. In an emitter follower, the output voltage is         1. 180o out of phase from the input voltage         2. 90o out of phase from the input voltage         3. in phase with the input voltage         4. None  55. A silicon controlled rectifier can be considered to be:         1. Two pnp transistor connected back to back         2. Two npn transistor connected back to back         3. One npn and one pnp transistor connected back to back         4. Two zener diodes connected back to back  56. A rf signal contains three frequency components 870 KHz, 875 KHz 880 KHz. This signal needs to be amplified. The amplifier used should be         1. Audio frequency amplifier         2. Wide band amplifier         3. Push pull amplifier         4. None  57. In the emitter follower circuit         1. The output current and voltage are inphase with the input current and voltage respectively         2. The input and output impedances are equal         3. There is current series negative feedback         4. The output impedance is much higher than the input impedance  58. The frequency response of a system is the range of frequencies between the upper and lower         1. 1 dB points         2. 6 dB points         3. 3 dB points         4. None  59. In a class C amplifier the output current is zero for         1. Half cycle         2. Full cycle         3. Less than half cycle         4. More than half cycle

  60. When RL [load resistance] equals the internal resistance of a generator, which of the following is maximum:         1. Power in RL         2. Current through RL         3. Voltage across RL         4. Efficiency of the circuit  61. negative feedback in an amplifier results in:         1. increased gain and increased bandwidth         2. increased gain and reduced bandwidth         3. reduced gain and increased bandwidth         4. reduced gain and reduced bandwidth  62. A class B push-pull amplifier suffers from         1. Cross-over distortion         2. Excessive harmonic distortion         3. Inter modulation distortion         4. None  63. An oscillator of the LC type that has split capacitor in the tank circuit is         1.  Hartely oscillator         2. Wein bridge oscillator         3. Colpitts oscillator         4. None  64. Clamping circuits are also known as         1. AC restorer         2. DC restorer         3. Voltage to frequency converter         4. None  65. Which of the following has the greater mobility         1. Positive ion         2. Negative ion         3. Electrons         4. Holes  66. An N type semiconductor as a whole is         1. Positively charged         2. Electrically neutral         3. Negatively charged         4. None  67. In a semiconductor, the forbidden energy gap is of the order         1. 1 ev            b. 6 ev            c. 7 ev          d. 0.1 ev  68. In LED, light is emitted because         1. Recombination of charges take place         2. We make the light fall on LED         3. Diode emits light when heated         4. None  69. UJT is also called         1. A voltage controlled device         2. A current controlled device         3. A relaxation oscillator         4. None

  70. The transistor configuration which provides higher output impedance is         1. CC        b. CB           c. CE         d. None  71. Tunnel diodes are fabricated from         1. Silicon         2. Germanium         3. Either silicon or germanium         4. Either germanium or gallium  72. N channel FETs are superior to P channel FETs because         1. They have a higher input impedance         2. They have a high switching time         3. They consume less power         4. Mobility of electrons is greater than that of holes  73. Diac is a solid state device which works as a         1. 2 terminal bidirectional switch         2. 2 terminal unilateral switch         3. 3 terminal bidirectional switch         4. None  74. Triac is a solid device which works as a         1. 2 terminal bidirectional switch         2. 3 terminal bidirectional switch         3. 4 terminal bidirectional switch         4. 2 terminal unilateral switch  75. Compared to a CB amplifier, a CE amplifier has         1. Lower input resistance         2. Higher output resistance         3. Lower current amplification         4. Higher current amplification  76. The input and output signals of a common emitter amplifier are:         1. Always equal         2. Out of phase         3. In phase         4. Always negative  77. The operation of a JEET involves         1. A flow of minority carriers         2. A flow of majority carriers         3. Recombination         4. Negative resistance  78. Solar cell is an example of a         1. Photo conductive device         2. Photo emissive device         3. Photo voltage device         4. None  79. Bretters and bolometers are used in the measurement of         1. Microwave power         2. VSWR         3. Transmission losses         4. None  80. A klystron operates on the principle of

         1. Velocity modulation         2. Amplitude modulation         3. Pulse modulation         4. Frequency modulation  81. The unit of the amplification factor of a triode is         1. Decibels         2. Volt         3. Neper         4. None  82. A change in base current from 30 to 40 mA changes the collector current from 500 to 900 mA. The B factor for this power transistor equals         1. 900           b. 500              c. 3             d. 40  83. The field effect transistor can be used as         1. Variable capacitance         2. A constant voltage source         3. A variable resistance         4. A constant current source  84. Why NPN transistor are preferred over PNP transistor         1. NPN transistor have low heat dissipation         2. NPN transistor can handle large power         3. NPN transistor are cheap and easily available         4. None  85. The germanium transistors are seldom used above         1. 60oC         b. 75oC           c. 125oC        d. 175oC  86. In a FET the drain voltage above which there is no increase in the drain current is called         1. Pick off voltage         2. Critical voltage         3. Pinch off voltage         4. Break down voltage  87. A reflex klystron has         1. Only one cavity working both as the buncher & the catcher         2. Two cavities one for buncher and one for the catcher         3. Three cavities, two for buncher and one for catcher         4. No cavity at all  88. Bipolar junction transistors are seldom used as switching devices because         1. BJTs are not economical fro using as switching devices         2. They can handle only high voltage but not high currents         3. They need separate circuits when used as switching device         4. Of slow response and inability to withstand high voltage  89. The voltage at which the electron flow starts from the anode is called         1. Break down voltage         2. Peak inverse voltage         3. Peak voltage         4. Pinch off voltage  90. The heater filament of a vacuum tube is generally supplied with AC voltage (and not DC voltage) for heating because         1. It results in a uniform heating of filament so that the electron emission also uniform         2. It is very easy to obtain AC voltage from AC power mains

         3. The DC voltage that would be required for heating has much greater magnitude than the AC voltage         4. When DC is used for heating, a different type of filament is required which very expensive  91. The dopant used for P type semiconductor is         1. Phosphorous         2. Boron         3. Carbon         4. Sodium  92. An example of negative resistance characteristic device         1. BJT        b. MOSFET           c. UJT         d. PINdiode  93. The average DC voltage obtained from a bridge rectifier with a sine wave input V sin wt is         1. V / 2        b. 2V           c. 4V              d. V  94. The maximum theoretical efficiency of a class B amplifier is         1. About 20%         2. About 50%         3. About 75%         4. 100%  95. A cascade amplifier is         1. A CE amplifier followed by CC amplifier         2. A CE amplifier followed by CB amplifier         3. A CC amplifier followed by CB amplifier         4. A CB amplifier followed by CE amplifier  96. Toggle switches can be debounced using         1. Astable multivibrator         2. Shift register         3. RS flip flop         4. None  97. A band pass filter has a centre frequency at 5 KHz. The 3 dB cut off frequencies are 4.5 KHz and 5.5 KHz. The Q factor of the filter is         1. 5        b. 0.2         c. 5.2          d. 0.45  98. The domestic buzzer makes use of         1. Hall effect         2. Tunneling effect         3. Natural resonance         4. Piezoelectric effect  99. The device which uses avalanche breakdown is         1. PIN diode         2. Zener diode         3. Impart diode         4. GUNN diode 100. The correct relation between Alpha and Beta of a transistor is         1. a / b-1         b.b=a-1        c. b = a / 1-a        d. a = b + 1/ b

Answer

1.      d

2.      b

3.      a

4.      b

5.      a

6.      b

7.      d

8.      c

9.      c

10.  a

11.  d

12.  c

13.  c

14.  b

15.  c

16.  c

17.  c

18.  a

19.  b

20.  d

21.  d

22.  d

23.  c

24.  a

25.  a

26.  b

27.  d

28.  d

29.  b

30.  d

31.  b

32.  a

33.  d

34.  c

35.  d

36.  d

37.  b

38.  a

39.  c

40.  a

41.  b

42.  c

43.  c

44.  c

45.  c

46.  c

47.  d

48.  c

49.  c

50.  a

51.  a

52.  d

53.  c

54.  c

55.  c

56.  d

57.  c

58.  c

59.  c

60.  a

61.  c

62.  a

63.  c

64.  b

65.  c

66.  b

67.  a

68.  a

69.  a

70.  b

71.  d

72.  d

73.  a

74.  b

75.  d

76.  b

77.  b

78.  c

79.  a

80.  a

81.  d

82.  d

83.  c

84.  d

85.  b

86.  c

87.  a

88.  d

89.  b

90.  b

91.  b

92.  c

93.  d

94.  b

95.  b

96.  c

97.  a

98.  d

99.  c

100.c

Hi Friends

I’m Gaurav Kumar. I am from HCTM kaithal. I have gave the written exam of BEL for probationary engineer.

Their selection procedure consists of 2 stages written (technical+ apti.) and interview.

I’m from ECE and the written test consists of general questions. most of them from control system and network.  I expected the cut-off for the written examination was 100 out of 150. After clearing the written I face the interview. Interview panel comprise of 5 members from electronics, computer, mechanical & HRD field. Most of the questions asked in the interview were simple like some electronics principles and their applications.

Here I have given some of the questions of the written paper (ECE)...

1-right answer

.25-wrong answer

1.   Data interpretation containing bar and pie chart in one question.

2.   What is p.m and gain margin for stability-positive or negative?

3.   Tunnel diode is a heavily doped p-n junction diode.

4.   What is the dual of parallel r-c n/w.

5.   Relationship puzzle.

6.   Find phase crossover frequency when g(s)h(s) is given.

7.   Question from pattern of radiation of different antenna.

8.   The e. m wave varies as distance.-1/r,1/r2.

9.   A transfer function having pole at right side is non-minimum phase system.

10.  Proportional derivative controlled system has high sensitivity.

11.  Lapalce transform of 1-10e-st.

12.  Integration of cos2t dt.

13.  The no. of samples for a convolution x(n), y(n) having x(n) of length 5 and y(n) of length 6.

14.  State space representation find transfer matrix given a liner equation

15.  The value of carrier power when total power =10kw,m=0.6.

16.  Superposition theorem is used for I,v,p..

17.  Given a form equation in standard form find frequency deviation.

18.  The source of microwaves is klystron, impatt, twt, and magnetron.

19.  Question on formulas of a-d and d-a converter.

20.  In a squarer if 4 bit data is squared then the no of data lines and address lines are

21.  Given a g(s) h(s) what is the no of zeros at infinity.

22.  For a two circuit abcd parameter are given find the abcd parameter of cascaded ckt.

23.  Question from transducer on tooth rotor.

24.  Question on rubidium laser for its excitation.

25.  Question from management point of view.

26.  One easy puzzle of six rows one upon each other.

27.  If a charge is at 002 and at 00-2 then electric field is in the direction of

28.  The no. Of nand gate to implement a+ (nota) b+a (notb) c.

Thank you and best of luck

General Aptitude:  Data interpretation questions and passage (reading) ques - around 20 questions. some logical analysing questions (were simple)

1. Given probability for A to fail 0.5 and for B to fail 0.3 then what is the probability of either A or B fail?

2. Rita told mani tht,"I saw a girl yesterday who is the youngest daughter of brother in law of my friend's mother" what is the relation between her friend and the girl she saw ?ans: cousin (chk)

3. 750 hrs of quality test was conducted on 10 components, at the end of 350 hr, a component failed. What is the probability of failure per hour?

4. Given the P(A) and P(B) and probability of occurence of both... try to know the logic to find probaility of neither A nor B. 

1. Numerical problem based on modulation index fc, fm.... (formula based direct question).

2. Poles & zeroes are at .01,1,20,100... find phase margin/angle at f=50Hz.ans -90 (By drawing bode plot)

3. In n-type enhancement mode MOSFET drain current-------- options are- increase/decrease with inc/dec in drain/gate voltage.  ans(d)

4. Gain of an directional antenna 6db P=1mw find transmitted power..... (use Ptr= G * P.)

5. Multiplication of two nos 10101010 & 10010011 in 2's complement form..

6. A ckt is given supplied with 15v with a series of resistance of 1k and a parallel combination of 12V zener diode and 2k resistance. Find current through 2k resistance.      ans: 6mA

7. A MP has 16 line data bus & 12 line addr bus find memory range....Ans..4K(4*1024bytes)

8. Divide by 12 counter require minimum ..... no of flip flopsAns. 4

9. Storage time in p-n junction.

10. Successive approx. use in ....Ans ADC(analog to digital)

11. Pre-emphasis require in ...... low freq/high freq signal.

12. Handshake in MP .....Ans. to communicate with slower peripherals.

13. Binary equivalent of 0.0625Ans. 0.0001

14. Which code is self complement of itself

15. Excess three code of an given binary no.

16. When we add 6 in BCD operations....  Ans. if result exceed valid BCD nos.

17. Shottky diode has better switching capability because it switch between....

18. Figure of Merit is same as......

19. Switching in diode happens when....

20. During forward bias majority charge conc. in depletion layers inc/decrease....

21. Channel capacity depend on....Ans. Usable frequency or bandwidth

22. A 2kHz signal is passed through an Low pass filter having cut-off freq 800Hz o/p will be

23. Carrier amplitude 1v,  peak to peak message signal 3mv find modulation index.

24. A 12V signal is quantized into two V/14 & 6 equal V/7 determine quantization error. 

Part II True & false (10 - 1 mark each) with 50% -ve marking1. Power dissipation in ECL is minimum.... False2. Fourier Transform of a symmetric conjugate function is always real.... True3. Divide by 12 counter requires a minimum of 4 flip flops.... True4. Boron can be use as impurity to analyse base of a npn transistor.... True 

1) in analog question based on zener diode

2) coupling capacitors and bypass capacitors affect

3) 1,8,27,64,125, ... which among the following will not come in the seriesa.1000,  b.729   c.259

4) which of the following game uses bulleya.football  b.cricket   c.goalf..  d.hockey

5) a zener diode works on the principle of 

6)under the high electric field,in a semiconductor with increasing electric field

7)in an 8085, microprocessor system with memory mapped I/O

8)built-in potential in a p-n jn.-

9)the breakdown voltage of a transitor with its base open is BV(ceo) and that with emitter open BV(cbo) then

10) ques based on half adder

11) based on flip flop

12) block diagram reduction

13) to find max overshoot (2 ques based on it)

1.which of the following game uses bulleya.football  b.cricket   c.goalf..  d.hockey

2.coupling capacitors and bypass capacitors affectAns:Only affect the lower cut off frequencies

3.1,8,27,64,125, ..........,.......which among the following will not come in the seriesa.1000,  b.729   c.259Hint:1³, 2³, 3³, 4³,5³,..... the series is like that

4. one image question.the question is RC coupled amplifier with a feed back network in between Collector and Base. Which type of feedback is this?

a.Current series b.Voltage shunt  C. voltage series  d current shuntAns: Voltage shunt

5.Block reduction of control system(simple)

6.settling time of Control system. Given the transfer function.Ans== 4/?wn<!--[if !vml]--><!--[endif]-->

7.Dual of a logical expression

8.Particular Integral of homogenious eqn

1) 1,8,27,64,125... which element does nt belong to the above series.(i) 259  (ii)729  (iii) 1000  (iv) 512.     ans:(i)

some technical questions(1)the breakdown voltage of a transitor with its base open is BV(ceo) and that with emitter open BV(cbo) then,ans: BV(cbo)>BV(ceo)

(2)a zener diode works on the principle of ans:tunneling of charge carriers across the jn.

(3)under the high electric field, in a semiconductor with increasing electric field-ans:the drift velocity of charge carriers saturate.

(4) built-in potential in a p-n jn.-(i) is equal to the difference in the fermi level of the two sides,expressed in volts.(ii) increased with increase in doping levels of the two sides.(iii)increse  with the increase in temp.(iv)all the above.ans : (iv)

(5) in an 8085, microprocessor system with memory mapped I/O:(i) I/O device have 8-bit addresses.(ii)I/O devices are accessed using IN and OUT instructions.(iii)there can be a max of 256 input devices and 256 output devices.(iv) airthmetic  and logic operations can be directly performed with the I/Odata.ans : (iv)

Part I"Objective questions (40 with 1.5 marks each) with 50% -ve marking.

1. Numerical problem based on modulation index fc, fm. (formula based direct queston).

2. Poles & zeroes are at .01,1,20,100  find phase margin/angle at f=50Hz.       ans -90(By drawing bode plot)

3. In n-type enhancement mode MOSFET drain current"""" options are- increase/decrease with inc/dec in drain/gate voltage. ans(d)

4. Gain of an directional antenna 6db P=1mw find transmitted power(use Ptr= G * P.)

5. Multiplication of two nos 10101010 &  10010011 in 2's complement form..

6. A ckt is given suppplied with 15v with a series of resistance of 1k and a parallel combination of 12V zener diode and 2k resistance. FInd current through 2k resistance. Ans: 6mA

7.A MP has 16 line data bus & 12 line addr bus find memory range.Ans..4K(4*1024bytes)

8.Divide by 12 counter require minimum .. no of flip flops         Ans. 4

9.Storage time in p-n junction.

10.Succesive approx. use in .         Ans ADC(analog to digital)

11.Pre-emphasis require in  low freq/high freq signal.

12.Handshake in MP ..  Ans to communicate with slower peripherals.

13. Binary equivalent of 0.0625      Ans. 0.0001

14.Which code is self complement of itself

15.Excess three code of an given binary no.

16.When we add 6 in BCD operations.  Ans. if result exceed valid BCD nos.

17.Shottky diode has better switching capability because it switch between.

18.Figure of Merit is same as

19.Swithcing in diode happens when.

20.During forward bias majority charge conc. in depletion layers inc/decrease..

21.Channel capacity depend on.    Ans. Usable frequency or bandwidth

22.A 2kHz signal is passed through an Low pass filter having cut-off freq 800Hz o/p will be

23. Carrier amplitude 1v,  peak to peak message signal 3mv find modulation index.

24.A 12V signal is quantized into two V/14 & 6 equal V/7 determine quantization error.

Part II True & false...(10 1 mark each) with 50% -ve marking

1.Power dissipation in ECL is minimum. False

2.Fourier Transform of a symmetric conjugate function is always real . True

3.Divide by 12 counter requires a minimum of 4 flip flops.True

4.Boron can be use as impurity to analyse base of a npn transistor.True

Other Question Placement Paper : 

1)  in analog question based on zener diode

2) coupling capacitors and bypass capacitors affect

3) 1,8,27,64,125, .,.which among the following will not come in the seriesa.1000,  b.729   c.259

4) which of the following game uses bulley a.football   b.cricket    c.goalf..   d.hockey

5) a zener diode works on the principle of

6)under the high electric field,in a semiconductor with increasing electric field

7)in an 8085,microprocessor system with memory mapped I/O

8)built-in potential in a p-n jn.-

9)the breakdown voltage of a transitor with its base open is BV(ceo) and that with emitter open BV(cbo) then

10) ques based on half adder

11) based on flip flop

12) block diagram reduction

13) to find max overshoot (2 ques based on it)

Paper: BEL Placement Paper (Technical-Electronics-IVth)

  1. The register is a         1. Simplified unit of a subtractor         2. Cascaded group of the flip-flop         3. Binary ripple counter         4. Data selector   2. The energy of the photo electron depends upon the following factor         1. Intensity of incident radiation         2. Quality of the photocathode         3. Frequency of incident radiation         4. Type of the incident light source   3. Hall effect is used to determine         1. Magnetic flux         2. Current density         3. Type of semiconductor material         4. All of the above   4. Which one of the following is the thermistor         1. Semiconductor device         2. Microwave device         3. Platinum resistance thermometer         4. Thermo-couple device   5. Silicon is having direct band gap         1. True         2. False         3. No gap         4. None of these   6. Boron is doped in silicon to form         1. P-type         2. N-type         3. Intrinsic         4. None of these   7. The concentration of impurity in doped silicon semiconductor per atom is         1. 1018         b. 1022        c.108           d.10-22   8. Conduction in P-type semiconductor is due to         1. Movement of hole         2. Movement of electron         3. Movement of atoms         4. Movement of electron-hole pair   9. Slope of electrical conductivity Vs temperature in semiconductor is         1. Positive         2. Negative

         3. Linear         4. No effect  10. Volt equivalent of temperature of silicon at room temperature (300 deg K) is         1. 0.7V         b. 1.1V          c. 0.026V              d. 16V  11. Carbon is not used as semiconductor because         1. It does not belong to silicon group         2. It is a good conductor         3. It is not a conductor         4. Band gap is very high  12. In forward bias of P-N junction depletion region         1. Increases         2. Decreases         3. Remains the same         4. Breaks down  13. Knee voltage in diode stands for         1. Reverse break down voltage         2. Saturation voltage         3. Threshold of current conduction         4. Peak inverse voltage  14. An ideal semiconductor diode for an AC input acts like         1. Unidirectional switch         2. Bidirectional switch         3. Cuts off  AC part         4. Power booster  15. Reverse saturation current in P-N junction diode is due to         1. Hole conduction         2. Electron conduction         3. Minority carrier conduction         4. Majority carrier conduction  16. In the zener diode the break down in the reverse characteristic current is due to         1. Electrons         2. Hole         3. Electron hole pair         4. Crystal ions  17. The percentage of voltage regulation is defined as         1. V no load " V load      r100  / V load         2. V  load " V no load      r100  / V load         3. V  load " V no load      r100  / V no load         4. V no load   r100 / V load  18. Filtering is effected by shunting the load with a         1. Capacitor         2. Resistor         3. Inductor         4. None of these  19. Without applying the biasing voltage the transistor current would be         1. Maximum         2. Minimum         3. No change

         4. Zero  20. In the transistor the doping at the emitter is much larger than the base results in         1. Emitter current entirely of holes         2. Emitter current entirely of electrons         3. Base current is due to electron-hole pair         4. Emitter does contribute carrier which can reach collector  21. The largest current carrying component in P-N-P transistor is         1. Electrons         2. Holes         3. Electron hole pair         4. Silicon atoms  22. The circuit shown in the figure represents         1. Rectifier         2. Clamping circuit         3. Clipping circuit         4. Low pass filter 

  23. Clamping circuit is used for         1. AC to DC conversion         2. Biasing         3. Limiting the amplitude         4. Wave shaping  24. For ideal clipping circuit one should use a diode with cut-in voltage         1. 0.7V         b.1.1V         c. 0V           d. 0.2V  25. The ratio of peak inverse voltage of full wave and half wave rectifier is         1. 1           b. 2          c. 1/2             d. 1/4  26. Which of the following transistor configuration is a power amplifier         1. Common emitter         2. Common base         3. Common collector         4. All of the above  27. In a active mode of a transistor, collector conduction takes place due to         1. Majority carrier         2. Minority carrier         3. Common collector         4. All of the above  28. Common emitter configuration is used for a         1. Current amplification         2. Voltage amplification         3. Current and voltage amplification         4. Charge amplification  29. The transistor configuration where input is emitter and output is collector is called:         1. Common emitter         2. Common base common collector         3. Voltage follower(current gain)  30. Beta of a transistor is given by         1. Ib/Ic         b. Ic/Ib          c. Ib/Ie            d. Ic/Ie  31. Germanium transistor is preferred over silicon transistor in the following application

         1. High frequency         2. High power         3. Low voltage         4. Power rectification  32. SCR is based on the principle of         1. Voltage regeneration         2. Current regeneration         3. Power regeneration         4. Power rectification  33. The number of clock pulses arriving at the digital counter input, should be in the form of         1. Decimal         2. Binary         3. Octal         4. Hexadecimal  34. In which of the counter the clock input is common to all flip flops         1. Asynchronous counter         2. Synchronous counter         3. Decade counter         4. Down counter  35. Multiplexer helps in which of the following         1. Repetition of similar circuit construction         2. Selecting all the signal at the output at the same time         3. Prevention of constructing similar circuits         4. Increase in the constructional costs due to repetition circuits  36. Full adder for two inputs can be developed with the help of         1. Two half adder on OR gate         2. One half adder and two OR gate         3. An EXOR gate and AND gate         4. Two AND gates and an OR gate  37. The important use of gray code is for a         1. Ripple counter         2. Full adder         3. Encoder         4. Decoder  38. In which of the code only one bit changes at each time         1. BCD         2. Aiken code         3. Excess 3 code         4. Gray code  39. In Johnson code for N bits, the maximum number can be formed is given by an expression         1. 2.N        b. 2N        c. 2N " 2N           d. None of these  40. The active mode of transistor operation is used in log circuits because of its         1. Non linearity         2. Linearity         3. Switching nature         4. High speed

  41. Intermediate frequency in television receiver is         1. 26-46 MHz         2. 1.6-2.3 MHz         3. 455-KHz         4. None of these  42. At absolute temperature, a silicon crystal acts like an insulator because         1. Electrons cannot move through a crystal         2. Electrons are tightly held by other atoms         3. Electrons can break away only by supplying energy         4. All of the above  43. Extrinsic semiconductor is         1. Doped with impurities         2. Exists in the pure state         3. N-type only         4. Only P-type  44. The process of extracting the audio information from the modulated envelope is called         1. Modulation         2. Detection         3. Transmission         4. Oscillation  45. Selectivity of a radio receiver is defined as         1. Ability to reproduce the original frequencies         2. Ability to eliminate wanted frequencies         3. Ability to reject unwanted frequencies         4. Ability to pick up the weak signal  46. Digital counter cannot be used as         1. Clock         2. Timer         3. Event counter         4. Multiplier  47. Distortion in the amplifier is due to         1. Non linearity of the device         2. Inductance presents in the circuits         3. Capacitance         4. Stray effect  48. The purpose of RF amplifier tuning in the radio receiver is         1. To reject all the frequencies         2. To select all the frequencies         3. Only to select required frequencies & amplification         4. To vary the band width  49. The intermediate frequency used in the radio receiver is         1. 455KHz        b. 1.6 MHz        c. 20 MHz             d. 60 MHz  50. The purpose of using tuned circuit between stages in the radio receiver is         1. To increase the selectivity         2. To increase the sensitivity         3. To increase both selectivity and sensitivity         4. To get the detector output

  51. In an amplifier, the frequency characteristic may be divided into how many regions         1. Two     b. Three         c. Four       d. Zero  52. Op.amp. has high input impedance because         1. High band width         2. Differential amplifier         3. Current source at input end         4. Common collector configuration  53. Gain of an OP amp. In inverting mode is "Rf / Rn provided, the OP.amp. has         1. Low output impedance         2. Low input bias current         3. High CMRR         4. High open loop gain  54. Slew rate of an OP.amp.is         1. Change of O/p voltage with time         2. Propagation speed         3. Input RC time constant         4. Off set voltage drift  55. Instrumentation OP.amp. is used in application where         1. Two instrument are to be interfaced         2. Input is very low level signal         3. DC signals are involved         4. Differential signals are involved  56. An OP.amp. integrater will be         1. Capacitor at input         2. Diode at input         3. Diode feed back         4. Capacitor feed back  57. A logarithmic amplifier will have         1. Inductor feed back         2. Diode feed back         3. Resistance feed back         4. Thermistor feed back  58. OP.amp. can be converted into capacitor by         1. Increasing bandwidth         2. Removing feed back         3. Increasing input impedance         4. Positive feed back  59. Comparators are used as         1. Switching device         2. Linear amplifiers         3. Power amplifiers         4. High speed amplifiers  60. Typical output impedance of 741 OP amps. is         1. 0.5 W        b. 1 K W        c. 1 W           d. 75 W  61. Typical unity gain bandwidth of 741 OP amps. is         1. 10 MHz        b. 100 KHz        c. 1 MHz            d. 1.5 MHz  62. OP.amp. wein bridge oscillator works when the over all gain is         1. 180         b. 3          c. 1.2             d. 125

  63. Important part in a electronic voltage regulator is         1. Error amplifier         2. External pass transistor         3. Reference voltage diode         4. All the above  64. To generate a triangular wave form from a square wave         1. Differentiator is used         2. Integrator is used         3. Logarithmic amplifier is used         4. Clipping circuit is used  65. For multiplying two analog signals which one of the following is used         1. Comparator         2. Hall effect device         3. Gunn diode         4. Tunnel diode  66. Which of the following device is used as an electronic memory element         1. Astable multivibrator         2. Monostable multivibrator         3. Magnetic tape         4. None of these  67. Phase sensitive detector in lock-in-amplifier is used         1. To increase the sensitivity of an instrument         2. To limit the bandwidth         3. To increase the dynamic range of the signal         4. To increase the input impedance  68. In television transmission video signal is         1. Frequency modulated         2. Amplitude modulated         3. Phase modulated         4. delta modulated  69. The Boolean function XYZ + YZ + XZ, after simplification gives         1. X           b. Y        c. Z               d. X+Y+Z  70. Extremely low power dissipation and low cost per gate can be achieved in         1. MOS ICs         2. CMOS ICs         3. TTL ICs         4. ECL ICs  71. Which of the following digital IC families can give maximum fan-out         1. ECL        b. PMOS         c. HTL           d.  CMOS  72. A punched card has         1. 22 rows, 90 columns         2. 12 rows, 80 columns         3. 12 rows, 2 columns         4. 8 rows, 128 columns  73. Which one of the  following is a 16 bit microprocessor         1. Zilog 80         2. Intel 8085         3. Motorola 6800

         4. Intel 8086  74. (0.3125)10    when converted to base 8 gives         1. (0.16)8         b. (0.26)8        c. (0.24)8        d. (0.124)8  75. Excess " 3 code is a         1. Weighted code         2. Cyclic code         3. Error correcting code         4. Self complementing code  76. ASC II code is a         1. Error detecting code         2. Self correcting code         3. An alphanumeric code         4. A weighted code  77. Modulo " 2 addition is represented by         1. f = XY + XY         2. f = XY + XY         3. f = X + XY         4. f = XY + XZ + YZ  78. Which one of the following Boolean identities is correct?         1. XYZ + YZ + XZ = YZ + XZ         2. XYZ + YZ +XZ = XY + XZ         3. XY +XZ = XY + XZ + YZ         4. X + XY = XY  79. SN7410 IC is a         1. Quad 2 input NAND gate         2. Triple 3 input NAND gate         3. Dual M/S J-K flip flop         4. None of these  80. Intel 8085 microprocessor has two registers known as primary data pointers these are         1. Registers V & C         2. Registers D & E         3. Registers H & L         4. None of these  81. Intel 8080 microprocessor has an instruction set of 91 instructions. The  op-code to implement the instruction set should be at least         1. 6 bit          b. 7 bytes          c. 7 bit           d. 8 bit  82. A micro programmed computer can have the following memories in its control memory unit         1. Semiconductor ROM         2. Semiconductor RAM         3. Magnetic RAM         4. None of these  83. In digital circuits parallel operation is preferred because         1. It requires less memory         2. Circuitry is simple         3. It is faster than series operation         4. For None of these of the above reasons

  84. SN 7401 IC is a         1. Quad 2 input NAND gate         2. Quad 2 input NAND gate with open collector output         3. Quad single input NAND gate with open collector output         4. None of these  85. What is the binary code of (26)?         1. 11001       b. 10001             c.  11010         d. 10100  86. The basic RS flip flops is         1. A bistable multivibrator         2. A monostable multivibrator         3. An astable multivibrator         4. None of these  87. The input impedance of an operational amplifier is         1. Very small         2. Zero         3. Very high but not infinite         4. Infinite  88. Sn 7411 is         1. OP.amp. monolithic and short circuit protection in-built         2. Two input NAND gate         3. Three input NAND gate with open collector output         4. None of these  89. The output voltage of an operational amplifier is         1. 90 deg out of phase from the input         2. 90 deg out of phase from the input         3.  45 deg out of phase from the input         4. 180deg out of phase from the input  90. The equivalent octal number of (492) is         1. 574        b. 547         c. 754              d. 758  91. The equivalent decimal number for gray code 1011 is         1. 14       b. 13         c.  41             d. 31  92. The  output will be only if all inputs go to 1 in case of         1. OR gate       b. AND gate         c. NAND gate       d. NOT gate  93. Which of the following circuits is known as half adder?         1. AND circuit         2. OR circuit         3. Exclusive OR circuit         4. None of these  94. Which of the following memories is used to store variable quantities of the data?         1. RAM    b. ROM       c. PROM        d. EPROM  95. Large scale Integrated (LSI) circuits usually contain         1. Less than 10 gates         2. 10 to 100 gates         3. more than 100 gates         4. more than 1000 gates  96. The Boolean expression A + AB + B   on simplification can be reduced to:         1. 0       b. 1          c. A + B     d. A + B  97. For realizing a decade counter using flip-flops the minimum number of flip-flops

required is         1. 4           b. 5            c. 6               d. 10  98. Which logic family is widely used in SSI & MSI applications?         1. ECL         b. DTL          c. TTL         d. None of these  99. An amplitude modulation detector detects         1. The peak value of the modulation signal         2. The envelop of the modulation signal         3. The peak value of the carrier signal         4. The average value of the carrier signal 100. Microwave (MW) links are generally preferred to coaxial cable for TV transmission because:         1. They have less overall phase distortion         2. They are cheaper         3. Of their greater bandwidth         4. Of their relative immunity to impulse noise.

Answer

1.      b

2.      c

3.      d

4.      d

5.      a

6.      a

7.      a

8.      a

9.      b

10.  c

11.  b

12.  b

13.  c

14.  a

15.  c

16.  c

17.  a

18.  a

19.  b

20.  b

21.  b

22.  b

23.  c

24.  b

25.  a

26.  d

27.  a

28.  c

29.  b

30.  b

31.  b

32.  c

33.  b

34.  b

35.  a

36.  a

37.  c

38.  d

39.  b

40.  a

41.  d

42.  d

43.  a

44.  b

45.  c

46.  d

47.  a

48.  c

49.  a

50.  c

51.  c

52.  b

53.  d

54.  b

55.  b

56.  d

57.  d

58.  a

59.  a

60.  a

61.  a

62.  b

63.  d

64.  b

65.  a

66.  c

67.  b

68.  b

69.  c

70.  b

71.  d

72.  b

73.  d

74.  c

75.  d

76.  c

77.  a

78.  c

79.  b

80.  c

81.  c

82.  a

83.  b

84.  b

85.  c

86.  a

87.  c

88.  c

89.  d

90.  c

91.  b

92.  b

93.  c

94.  a

95.  c

96.  b

97.  a

98.  c

99.  b

100. A

Paper: BEL Placement Paper (Technical-Electronics-IInd)

1.      Resistivity of silicon in ohms cm. is approx. equal to

a.       50        b. 1012     c. 230k        d. 10-6

2.      Rsistivity  ofGermanium in ohms cm. is approx. equal to

a.       50        b. 10-12       c. 50k          d. 10-6

3.      The number of free electrons/cubic cm intrinsic Germanium at room temperature is approx. equal to

a.       1.5*1010      b. 2.5*1013      c. 1000       d. 5*106

4.      The number of free electrons/cubic cm of intrinsic  silicon at room temperature is approx. equal to

a.       1.5*1010      b. 2.5*1013     c. 10000      d. 5*106

5.      The forbidden energy gap for silicon is

a.       1.1eV         b. 067eV         c. 0.97eV       d. 1.7eV

6.      The forbidden energy gap for Germanium is

a.       1.1eV         b. 067eV         c. 0.97eV       d. 1.7eV

7.      N type material is formed by the addition of the following (penta valent )atom in n to semiconductor material

a.       Antimony

b.      Arsenic

c.       Phosphorous

d.      Any of the above

8.      P type material is formed by the addition of the following [Trivalent] atom tn to semiconductor material

a.       Boron   b. Gallium    c. Indium   d. Any of the above

9.      Impurity atoms that produces N type material by its addition in semiconductor is called

a.       Donar      b. Acceptor     c. Conductor      d. Insulator

10.  Impurity atoms that produces P type material by its addition in semiconductor is called

a.       Donar      b. Acceptor     c. Conductor      d. Insulator

11.  Dynamic resistance of a diode Rd is if voltage changes is DVd and the current change is D Id

a.       D Vd / D Id 

b.      D Id / D Vd

c.       1 / DVd

d.      1 / D Id

12.  Point contact diodes are preferred at very high frequency, because of its low junction

a.       Capacitance and inductance

b.      Inductance

c.       Capacitance

13.  Identify the circuit given below

a.       AND gate

b.      OR gate

c.       Rectifier

d.      NOR gate

14.  Identify the circuit given below

a.       AND gate

b.      OR gate

c.       Rectifier

d.      NOR gate

15.  DC value of a Half wave rectifier with Em as the peak value of the input is

a.       0.318Em

b.      0.418Em

c.       0.518Em

d.      0.618Em

16.  Change in Zener voltage of 10V at 100o C if temperature co-efficient is 0.072%o C as

a.       0.54 V   b. 0.74 V     c. 0.64 V        d. 0.14 V

17.  If Tc is th e% temperature co of /  oC  and Vz as zener voltage and T as change in temperature then the change in zener voltage is

a. 

b. 

c.       100. Vz. Tc  DT

d.      None of these of the above

18.  PIV for a full wave rectifier, if Em is the peak voltage is

a.       Em     b. 1.5Em       c. 0.636Em     d. 2Em

19.  Schottky Barrier diodes becomes important at

a.       DC level operation

b.      Low frequency operation

c.       High frequency operation

d.      None of these

20.  Clamping network is the one that will clamp the signal to a

a.       Different peak value

b.      Different DC level

c.       Different polarity level

d.      Different RMS level

21.  Clipping network is the one that will clip a portion of the

a.       Input signal without distorting the remaining portion

b.      Input signal with distorting the remaining portion

c.       Any of the above

d.      None of these

22.  Transition capacitance Ct of a Varicap diode with Knee voltage Vt, reverse voltage Vr and K, the constant based on semiconductor material and the construction technique & N dependent on type of junction is given by

a.       1 / K (Vt + Vr)N/2

b.      1 / K (Vt + Vr)N

c.       K / (Vt + Vr)N

d.      K / (Vt + Vr)1/N

23.  Ct = K / (Vt + Vr)N where Vt Knee voltage, Vr reverse voltage, K manufacturing dependent constant and N dependent on type of  junction, for alloy junction the value of N is

a.       1/3    b. 2/3    c. 1/2     d. 1/4

24.  Ct = K / (Vt + Vr)N where Vt Knee voltage, Vr reverse voltage, K manufacturing dependent constant and N dependent on type of  junction, for diffused junction the value of N is

a.       1/3    b. 2/3    c. 1/2     d. 1/4

25.  In JFET, the drain current Id is given by (Idss drain " source saturation current Vgs " Gate " source voltage, Vp the pinch off voltage)

a.       Idss[1 " Vp/Vgs]

b.      Idss(1 " Vgs/Vp)2

c.       Idss[1 " Vgs/Vp)

d.      Idss(1 " Vgs/Vp)3/2

26.  The shadow mask in colour tube is used to

a.       Reduce X-Ray emission

b.      Ensure each beam hits its own dots

c.       Increase screen brightness

d.      Provide degaussing for the screen

27.  Indicate which of the following signal is not transmitted in colour TV

a.       Y       b. Q      c. R     d. I

28.  Another name for horizontal retrace in TV receiver is the

a.       Ringing       b. Burst        c. Damper      d. Fly back

29.  Another name for the colour sync in the colour TV system

a.       Ringing       b. Burst        c. Damper      d. Fly back

30.  The HV anode supply for a picture tube of a TV receiver is generated in the

a.       Mains transformer

b.      Vertical output stage

c.       Horizontal output stage

d.      Horizontal oscillator

31.  The output of vertical amplifier is

a.       Direct current

b.      Amplified vertical sync pulse

c.       A saw tooth voltage

d.      A saw tooth current

32.  In a transistor if Alpha  = 0.98, current gain is equal to

a.       29      b. 59      c. 69       d.   49

33.  The active region in the common emitter configuration means

a.       Both collector and emitter junction is reverse biased

b.      The collector junction is forward biased and emitter junction

c.       The collector junction is reverse biased and emitter junction is forwared biased

d.      Both collector & emitter junction are forward biased

34.  The saturation region in the common emitter configuration means that

a.       Both collector & emitter junction are reverse biased

b.      The collector junction is forward biased and emitter junction

c.       The collector junction is reverse biased and emitter junction is forwared biased

d.      Both collector & emitter junction are forward biased

35.  The % of Red, Green & Blue in 100% White Y is given by

a.       30%, 59%, 11%

b.      50%, 30%, 11%

c.       30%, 11%, 50%

d.      33.3%, 33.5%, 38.3%

36.  Equalizing pulse width, if H is the Horizontal sync rate

a.       0.64 H     b. 0.07 H      c. 0.04 H      d. 0.16 H

37.  In a simple RC network the bandwidth is equal to

a.       1/2 p RC

b.      RC / 2

c.       2 C / p R

d.      2 p / RC

38.  The time constant of a RC network is given by

a.       RC      b. C/R       c. R/C       d. None of these

39.  First zero crossing of pulse frequency spectrum occurs at if d is the pulse width, T is the pulse repetition rate

a.       1/d      b. d/T       c. T/d        d. T

40.  The distortion less output characteristic of a network means

a.       Constant amplitude and linear phase shift over frequency

b.      Linear phase shift and amplitude need not be constant

c.       Any amplitude and phase

d.      None of these

41.  Single sideband means suppressed

a.       Carrier

b.      Carrier and one side band

c.       One side band

d.      None of these

42.  In an amplitude modulated signal, lower side band frequency is equal to (if the carrier frequency is fc and modulation frequency is fm)

a.       fm + fc       b. fc " fm      c. fm r fc      d. fc / fm

43.  Modulation index of the frequency modulation depends on

a.       Amplitude & frequency of the modulation signal

b.      Frequency and amplitude of carrier signal

c.       Carrier frequency

d.      None of these

44.  The BW of the narrow band FM if modulating frequency is fm

a.       3 r fm       b. 2 r fm        c. 2.5 r fm       d. 10 r fm

45.  Reactance tube modulator is known for

a.       FM       b. AM        c. PPM      d. PAM

46.  Bandwidth and rise time product is

a.       0.35    b. 0.45     c. 0.30     d. 0.49

47.  Energy gap, Lg, for Germanium at room temp [300o K] is

a.       0.72eV       b. 1.1eV      c. 1.53eV          d. 0.2eV

48.  Volt equivalent of temperature VT, at 116o K is

a.       0.11V     b. 0.01V       c. 1.16V       d. 0.1V

49.  Reverse saturation current of a Ge.diode is in the range of

a.       mA        b. uA       c. nA      d.  pA

50.  Cut-in voltage V for silicon is approximately

a.       0.2V       b. 0.6V      c. 0.9V      d. 1.1V

51.  Every 10o C rise in temp. the reverse saturation current

a.       Doubles 

b.      Halves

c.       Triples

d.      No change

52.  Hall effect with reference to Metal or Semiconductor carrying a current  I is placed in a transverse magnetic field B, an electric field E is induced in

a.       Parallel to B

b.      Perpendicular to I

c.       Perpendicular to both B & I

d.      Perpendicular to B

53.  1 eV (electron volt) is equal to:

a.       1.9 r 10-20 J

b.      1.6 r 10-19  J

c.       1.6 r 10-20 J

d.      1.16 r 10-19 J

54.  Donar impurity is having a valency of:

a.       2      b. 3       c. 4       d. 5

55.  Acceptor impurity is having a valency of

a.       2      b. 3        c. 4       d. 5

56.  Electron volt arises from the fact that if any electron falls through a potential of 1 volt, its kinetic energy will

a.       Decrease, & potential energy will increase

b.      Increase & potential energy decrease

c.       Be unaltered & potential energy decreases

d.      Increase & potential energy increase

57.  Hole is created in a semiconductor material if one of following impurities are added

a.       Antimony

b.      Arsenic

c.       Indium

d.      Phosphorus

58.  Excess electron is created by

a.       Boran

b.      Gallium

c.       Indium

d.      Arsenic

59.  A snubber circuit is used across the SCR to protect against

a.       The di/dt of the anode current

b.      The dv/dt turn on

c.       L.di/dt of load inductance

d.      None of these

60.  Germanium has the valency of

a.       2         b. 3        c. 4          d. 5

61.  Silicon has the valency of

a.       2       b. 3          c. 4            d. 5

62.  Hole acts as a free charge carrier of polarity

a.       Negative

b.      Positive

c.       Neutral

d.      None of these

63.  Burst signal in NTSC system is 8 cycles of the frequency of

a.       Colour sub carrier

b.      Picture carrier

c.       Sound carrier

d.      None of these

64.  Colour sub carrier reference burst is superimposed on the

a.       Back porch of the each horizontal sync pulse

b.      Front porch of the each horizontal sync pulse

c.       Front porch of the each vertical sync pulse

d.      Back porch of the each vertical sync pulse

65.  The law of mass action with reference to semiconductor technology states that the product of free negative & positive concentration is a constant and

a.       Independent of amount of donor and acceptor doping

b.      Dependent on amount of donor and independent of the amount acceptor impurity doping

c.       Depend on amount of both donor & acceptor impurity doping

d.      None of these

66.  The snubber circuit used across SCR is a simple

a.       R-L network

b.      RLC network

c.       LC network

d.      RC network

67.  To limit  the rate of rise of SCR anode current a small

a.       Inductor is inserted in cathode circuit

b.      Inductor is inserted in anode circuit

c.       Capacitor is inserted in anode circuit

d.      Capacitor is inserted in cathode circuit

68.  Torque developed by a DC servo motor is proportional to the

a.       Product of power and time

b.      Product of armature current and back emf

c.       Armature voltage and armature current

d.      Field voltage and field current

69.  Proportional Integral control

a.       Reduces steady state error but reduces the forward gain

b.      Increases the forward gain and reduces the steady state error

c.       Increases the steady state error and increases the forward gain

d.      None of these

70.  Increasing the servo bandwidth:

a.       Improves signal to noise ratio

b.      Improves speed response and lowers signal to noise ratio

c.       Improves power output

d.      None of these

71.  Notch filter is

a.       Low pass filter

b.      High pass filter

c.       Narrow stop band filter

d.      Narrow pass band filter

72.  In TV Receivers the Electron beam deflection method used is

a.       Electro static

b.      Electro magnetic

c.       Magnetic

d.      All the above

73.  In a line of sight communication the maximum range R in miles between the receiver antenna and transmitter antenna of height H in feet is approximately

a.       R = 1.93 Ã-H

b.      R = 1.23 Ã-H

c.       R = 1.53 Ã-H

d.      R = 2.03 Ã-H

74.  In wavelength of the 60 MHz carrier frequency is

a.       10 metres

b.      15 metres

c.       5 metres

d.      2.5 metres

75.  In standard TV receiving antenna the dipole element is

a.       0.5 of the wave length

b.      0.25 of the wave length

c.       1.5 of the wave length

d.      1.0 of the wave length

76.  The characteristics of FET are similar to:

a.       Triode

b.      Tertode

c.       Pentode

d.      Diode

77.  Charge coupled device is an array of capacitors whose structure is similar to:

a.       Shift register

b.      Flip-flop

c.       NAND gate

d.      Amplifier

78.  Operational amplifier characteristics are which of the following:

a.       Infinite gain

b.      Infinite input impedance

c.       Output impedance is zero

d.      All of the above

79.  The typical value of the open loop gain in dB of an amplifier at DC with no feedback is:

a.       90 to 100

b.      80 to 90

c.       0 to 50

d.      50 to 70

80.  The 3 dB band width means the frequency at which

a.       The open loop voltage gain reduced to 0.707

b.      The open loop gain reduced to unity

c.       Maximum voltage of a signal is without distortion

d.      It is a medium wave band width of radio receiver

81.  Rise time of an amplifier is defined as time required

a.       To change from 0 to 100 % of its final value

b.      To change from 0 to 50 % of its final value

c.       To change from 10 to 90 % of its final value

d.      To change from 10 to 100 % of its final value

82.  High speed amplifier design emphasized on

a.       Extremely small bandwidth

b.      Very slow response

c.       Unity gain bandwidth after 10 MHz

d.      None of these

83.  Tuned amplifier having the frequency range between

a.       150 KHz " 50 MHz

b.      100 Hz " 100 KHz

c.       100 KHz " 120 KHz

d.      50 MHz " 100 MHz

84.  The resonance frequency of a tuned circuit made up of R, L, C is given by

a.       1/2  pÃ-LC

b.      2 pÃ-LC

c.       2 p / Ã-LC

d.      Ã-LC / 2

85.  The voltage follower can be obtained using operational amplifier

a.       Without any feedback

b.      Series parallel feedback of unity

c.       Parallel feedback

d.      Series feedback

86.  Fidelity of the amplifier is when

a.       It is a linear amplifier

b.      It does not add or subtract any spectral components

c.       It amplifier each component by the same amount

d.      All of the above

87.  What would be the output when two input sine waves of frequency 50 KHz and 100 KHz passed through an amplifier in the medium signal

a.       50 KHz and 100 KHz

b.      100 KHz and 200 KHz

c.       50 KHz and 150 KHz

d.      All of the above

88.  The important application of Schmitt trigger is

a.       To convert slowly varying input voltage to abrupt voltage change

b.      To convert abruptly varying input voltage into slowly varying output

c.       To change the frequency of the input

d.      None of these

89.  Meaning of decoding is

a.       Binary addition

b.      Data transmission

c.       Demultiplexing

d.      Storage of binary information

90.  Approximately how many number of gates are incorporated in SSL chip

a.       12

b.      100

c.       Excess of 100

d.      Excess of  1000

91.  The circuit diagram represents which one of the following

a.       Half adder

b.      Full adder

c.       Exor gate

d.      AND gate

92.  Flip flop cannot be called as

a.       Bistable multivibrator

b.      1 Bit memory unit

c.       latch

d.      combinational circuit

93.  The important use of low pass filter in power supply is

a.       To get the regulation in the output voltage

b.      To filter out the ripple frequency

c.       To increase the current rating

d.      To convert AC into DC

94.  Binary equivalent of the decimal number 145 is

a.       10010001

b.      1001011

c.       1010001

d.      1100010

95.  In which of the following gate the output will be high when all the maintained at high level

a.       NOR

b.      AND

c.       NAND

d.      EXOR

96.  Which of the following definition is true in the De Morgan's theorem

a.       Multiplication symbols are replaced by addition symbol

b.      Addition symbols are replaced by Multiplication symbol

c.       Each of the terms are expressed in the complementary form

d.      All of the above

97.  8421/BCD code fro a decimal number 149 is

a.       0001 0100 1001

b.      10010101

c.       10101001

d.      None of these

98.  Combinational circuit are mainly characterized by

a.       Output depends upon the previous state & presents state

b.      Output depends upon the input at that particular instant

c.       Output depends upon the presents state & the clock state

d.      Output does not depends upon the input at all

99.  A flip flop is defined as

a.       A bistable device with two complementary outputs

b.      It is memory element

c.       It will respond to input and it is a basic memory element

d.      All of the above

100.          Four bit code is called

a.       Nibble

b.      Byte

c.       Word

d.      Register

Answer:-

1.      c

2.      a

3.      a

4.      b

5.      a

6.      b

7.      d

8.      d

9.      a

10.  b

11.  a

12.  c

13.  b

14.  a

15.  a

16.  a

17.  a

18.  d

19.  c

20.  b

21.  a

22.  c

23.  c

24.  a

25.  b

26.  b

27.  c

28.  d

29.  b

30.  c

31.  d

32.  d

33.  c

34.  d

35.  a

36.  c

37.  a

38.  d

39.  a

40.  a

41.  b

42.  b

43.  a

44.  b

45.  b

46.  a

47.  a

48.  b

49.  b

50.  b

51.  a

52.  c

53.  b

54.  b

55.  b

56.  b

57.  c

58.  d

59.  b

60.  c

61.  c

62.  b

63.  a

64.  a

65.  a

66.  d

67.  b

68.  b

69.  a

70.  b

71.  c

72.  c

73.  b

74.  c

75.  a

76.  c

77.  a

78.  d

79.  d

80.  a

81.  c

82.  c

83.  a

84.  a

85.  b

86.  d

87.  a

88.  a

89.  c

90.  a

91.  a

92.  d

93.  b

94.  a

95.  b

96.  d

97.  a

98.  b

99.  d

100.a

Paper: BEL Placement Paper (Technical-Electronics-IIIrd)

  1. The noise  figure of a receiver is a measure of:         1. Excess noise generated         2. Bandwidth of the receiver         3. Gain of the receiver         4. Operating frequency

2. The ratio receiver is:         1. Direct detection type         2. Super regenerative type         3. Super heterodyne type         4. None of these

3. In an amplitude modulation system, the modulation index is dependent upon:         1. Modulating frequency only         2. Carrier amplitude only         3. Modulating signal amplitude only         4. Modulating and carrier amplitudes only

4. Image rejection mixer is generally used:         1. To reject the unwanted signal         2. To improve signal amplitude         3. To improve noise figure         4. To improve conversion loss

5. The value of a resistor creating thermal noise is doubled. The noise power generated is therefore:         1. Halved         2. Quadrapuled         3. Doubled         4. Unchanged

6. Indicated the false statement:         1. HF mixer are generally noisier than HF amplifier         2. Impulse noise voltage is independent of bandwidth

         3. Thermal noise is independent of the frequency at which it is measured         4. Industrial noise is usually of the impulse type

7. If the carrier of a 100 percent modulated AM wave is suppressed the percentage power saving will be:         1. 50    b. 70        c. 100       d. 66.6

8. A balanced modulator produces:         1. The carrier and Two side bands         2. The carrier and one side band         3. Two side bands alone         4. Carrier and a number of side bands

9. The frequency deviation in FM system is proportional to:         1. Modulating frequency         2. Carrier amplitude         3. Modulating signal amplitude         4. None of these

10. In FM, the total transmitted power is:         1. Dependent on modulating signal amplitude         2. Dependent on modulating frequency         3. Dependent on modulating index         4. Independent of the above

11. The carrier in an FM system disappears for the lowest modulation index of:         1. 0.5         b. 1.0          c. 2.4            d. 3.5

12. The difference between phase and frequency modulation:         1. Is purely theoretical because they are the same in practice         2. Is too great to make the two systems compatible         3. Lies in the poorer audio response of phase modulation         4. Lies in the different definition of the modulation index

13. The overall noise figure of two cascaded amplifiers is equal to         1. The algebraic sum of the two         2. The sum of the squares of the two         3. The square root of the product of the two         4. None of these

14. The noise power output of an amplifier is equal to:         1. KTo BFG         2. KTo FG         3. KTo F/G         4. KTo / FG

15. The effective noise temperature of an amplifier is equal to         1. (F + 1) To

         2. FTo         3. (F " 1) To         4. None of these

16. The noise figure of an amplifier depends upon         1. Its bandwidth         2. Its gain         3. Its operating frequency         4. None of these

17. The velocity of electromagnetic wave in a coaxial cable is         1. Equal to the velocity in free space         2. Less than the velocity in free space         3. Greater than the velocity in free space         4. None of these

18. The standing wave ratio [SWR] in a transmission line:         1. Is proportional to the load impedance         2. Is dependent on the source impedance         3. Is a mis-match between the load and line         4. Is a measure of its power handling capability

19. The standing wave ratio (SWR) is unity in a transmission line if         1. The load impedance is equal to the characteristic impedance of the line         2. The load impedance is twice that of the characteristic impedance         3. The load impedance is half of the characteristic impedance of the line         4. None of these

20. The standing wave voltage node along a line repeats at the rate of if L is the wave length         1. L/4         b.L/2         c.L        d.2L

21. A quarter wave line when short circuited at the far end behaves like         1. Pure inductor         2. Pure capacitor         3. Parallel tuned circuit         4. Series tuned circuit

22. The stub line used to match transmission line with a given load impedance is generally         1. Another open circuited line         2. Another short circuited line         3. Quarter wave transmission line         4. Half wave transmission line

23. The smith chart generally covers a distance of         1. Quarter wavelength         2. Half wavelength

         3. One wavelength         4. Twice the wavelength

24. The component generally used to sample a portion of the energy transmitted in a line is         1. Isolator         2. Circulator         3. Directional coupler         4. None of these

25. The return loss in a transmission line is a measure of         1. Loss of the line         2. Standing wave ratio         3. Characteristic impedance of the line         4. None of these

26. The antenna can be considered as         1. Matching the source and free space         2. Matching the source to the line         3. Matching the line and free space         4. None of these

27. The free space impedance is approximately equal to         1. 177 W         2. 277 W         3. 377 W         4. 50 W

28. The polarization refers to         1. The physical orientation of the radiated wave         2. The directional of propagation of the wave         3. Direction perpendicular to the propagation of the wave         4. None of these

29. If u & e are the permeability and permittivity respectively the characteristic impedance of the medium is given by         1. ue             b. Ã-u/e        c. Ã-e/u        d. Ã-eu

30. The power density at distance 'r' from an isotropic radiator with transmitted power P is:         1. P/r2         2. P/2 p r2         3. P/4 p r2         4. None of these

31. Frequencies in the UHF range is normally propagated by means of         1. Ground waves         2. Sky waves

         3. Surface waves         4. Space waves

32. As electromagnetic waves travel in free space, only one of the following can happen to them         1. Absorption         2. Attenuation         3. Reflection         4. Refraction

33. High frequency waves are         1. Absorbed by the F2 layer         2. Reflected by the D layer         3. Affected by the solar cycle         4. Capable of use for long distance communications on the moon

34. Indicate which one of following terms applies to troposcatter propagation         1. SIDS         2. Fading         3. Fraday rotation         4. Atmospheric storms

35. When microwave signals follow the curvature of the earth, this in known as         1. Faraday effect         2. Ducting         3. Ionospheric reflection         4. Tropospheric scattering

36. An ungrounded antenna near the ground:         1. Is unlikely to need an earth mat         2. Acts as a single antenna of twice the height         3. Must be horizontally polarized         4. Acts as an antenna array

37. One of the following consists of non-resonant antenna:         1. The folded dipole         2. The rhombic antenna         3. The end fire array         4. The broad side array

38. Balun is:         1. A circuit element to connect balance line to unbalanced antenna or line:         2. A circuit element to connect balance line to balanced line         3. A circuit element to connect unbalance line to unbalanced line         4. None of these

39. The slotted line is used to measure:         1. Standing wave ratio

         2. Load impedance         3. Source impedance         4. None of these

40. In amplitude modulation Ec ( 1 + m Sin Wmt) Sin Wot, each side band amplitude will be:         1. Ecm/2         2. Ecm         3. Ec/m         4. 2Ec/m

41. FM modulation becomes equivalent to AM modulation if         1. FM index is greater than 1         2. FM index is equal to 1         3. FM index is very much less than 1         4. FM index less than or equal to 1

42. S/N improvement of FM over AM, B is the FM modulation index         1. 3B2          b.B              c.2B d.B/2

43. Picture transmission in TV employs         1. Suppressed carrier modulation         2. Vestigial side band         3. Single side band         4. None of these

44. Sound transmission in TV employ         1. Amplitude modulation         2. Phase modulation         3. Frequency modulation         4. Pulse amplitude modulation

45. One of the following is an indirect way of generating FM this is the:         1. Reactance FET modulator         2. Varacter divide modulator         3. Amstrong modulator         4. Reactance bipole transistor modulator

46. The modulation index of AM wave is changed from 0 to 1. The transmitted power is         1. Un-changed         2. Halved         3. Doubled         4. Increased by 50%

47. The isotropic antenna is represented by         1. Dipole antenna         2. Rhombic antenna         3. Yagi uda antenna

         4. No such antenna exists in practice

48. The gain of parabolic reflector antenna is proportional to         1. The diameter of the reflector         2. Square of the diameter of the reflector         3. Aperture area of the feed         4. None of these

49. The parabolic reflector antenna are generally used to         1. Provide high gain         2. Provide pencil beam         3. Increase bandwidth of operation         4. None of these

50. Cassegrain feed is used with a parabolic reflector to         1. Increase gain of the system         2. Increase the bandwidth of the system         3. Reduce the size of the main reflector         4. Allow the feed to be placed at a convenient point

51. A helical antenna is used for satellite tracking because of its         1. Circular polarization         2. Maneuverability         3. Broad bandwidth         4. Good front " to " back ratio

52. The discone antenna is         1. A useful direction finding antenna         2. Used as a radar receiving antenna         3. Circularly polarized like other circular antenna         4. Useful as a VHF receiving antenna

53. Waveguides are used mainly for microwave signals because         1. They depend on straight line propagation which applies to microwaves only         2. Losses would be too heavy at lower frequencies         3. There are no generators powerful enough to excite them at lower frequencies         4. They would be too bulky at lower frequencies

54. The wavelength in a waveguide         1. Is greater than in free space         2. Depends only on the waveguide dimensions and the free-space wavelength         3. Less than the free space wavelength         4. Equal to the free space wavelength

55. The dominant mode of propagation is preferres with rectangular waveguide because(indicate false statement)         1. It leads to the smallest waveguide dimensions         2. The resulting impedance can be matched directly to coaxial lines

         3. It is easier to excite than the other modes         4. Propagation of it without any spurious generation can be ensured

56. The velocity of propagation (group velocity) in a waveguide is         1. Less than the free space velocity         2. Greater than the free space velocity         3. Equal to be free space velocity         4. None of these

57. A wave can propagate in a waveguide if its cut off wavelength is         1. Greater than the free space wavelength         2. Less than the free space wavelength         3. Equal to be free space wavelength         4. None of these

58. The dominant mode in a rectangular waveguide is         1. TE11         b. TE10           c.TE20           d.TM11

59. The characteristic wave impedance of a waveguide         1. Depends on the mode of propagation         2. Does not depend on the mode of propagation         3. Is same as the free space impedance         4. None of these

60. A choke flange may be used to couple two waveguides         1. To help in the alignment of the waveguides         2. Because it is simpler than any other joint         3. To compensate the discontinuities at the joint         4. To increase the bandwidth of the system

61. The dominant mode in a circular waveguide is         1. TE01         b.TE11         c.TM01        d.TM11

62. A ferrite is         1. A non-conductor with magnetic properties         2. An inter metallic compound with particularly good conductivity         3. An insulator which heavily attenuates magnetic fields         4. A microwave semiconductor invented by farady

63. The maximum power that may be handled by a ferrite component is limited by the         1. Curie temperature         2. Saturation magnetization         3. Line width         4. Gyro magnetic resonance

64. The isolator is         1. Bidirectional         2. Unidirectional

         3. Used to tap the power in a waveguide transmission line         4. Used for None of these of the above

65. Isolator is generally used:         1. To protect the high power transmitter         2. To protect receiver         3. To protect the antenna         4. To avoid arcing in waveguides

66. A TR tube is used         1. To protect the high power transmitter         2. To protect receiver         3. To avoid arcing in waveguides         4. For None of these of the above

67. Rieke diagrams are used to select best operating conditions for         1. TWT amplifier         2. Klystron oscillator         3. Magnetron oscillator         4. Cross field amplifiers

68. The gain bandwidth product of a microwave transistor FT, is the frequency at which the         1. Alpha of the transistor falls by 3 dB         2. Beta of the transistor falls by 3 dB         3. Beta of the transistor falls to unity         4. Power gain of the transistor falls to unity

69. The cavity magnetron uses strapping to         1. Prevent mode jumping         2. Prevent cathode-back heating         3. Ensure bunching         4. Improve the phase-focussing effect

70. The transferred " electron bulk effect occurs in         1. Germanium         2. Gallium arsenide         3. Silicon         4. Metal semiconductor junction

71. One of the following is not used as a microwave mixer or detector         1. Crystal diode         2. Schottky " barrier diode         3. Backward diode         4. PIN diode

72.  SAW devices may be used as:         1. transmission media like stripline

         2. filters         3. UHF amplifiers         4. Oscillators at millimeter frequencies

73. Surface acoustic waves propagate in:         1. Gallium arsenide         2. Indium phosphide         3. Stripline         4. Quartz crystal

74. A parametric amplifier has an input and output frequency of 2.25 GHz, and is pumped at 4.5 GHz is a         1. Traveling wave amplifier         2. Degenerate amplifier         3. Lower-side band up converter         4. Upper-side band up converter

75. The negative resistance in a tunnel diode         1. Is maximum at the peak point of the characteristic         2. Is available between the peak and valley points         3. Is maximum at the valley point         4. May be improved by the reverse bias

76. Microwave links repeaters are typically 50KM apart         1. Because of atmospheric attenuation         2. Because of output tube power limitations         3. Because of Earth's curvature         4. To ensure that the applied voltage is not excessive

77. Microwave links are generally preferred to coaxial for television transmission because         1. They have less overall phase distortion         2. They are cheaper         3. Of their greater bandwidths         4. Of their relative immunity to impulse noise

78. A geostationary satellite         1. Is motionless in space(except for its spin)         2. Is not really stationary at all, but orbits the earth with a 24 hour period         3. Appears stationary over Earth's magnetic pole         4. Is located at a height of 35800KM to ensure global coverage

79. The geostationary satellite launched by India are called         1. INTELSAT         2. INSAT         3. COMSAT         4. MARISAT

80. A parametric amplifier must be cooled         1. Because parametric amplification generates a lot of hest         2. To increase bandwidth         3. Because it cannot operate at room temperature         4. To improve the noise performance

81. If the peak transmitted power in a Radar system is increased by a factor of 16, the maximum range will be increased by a factor of         1. 2           b. 4           c.8          d. 16

82. Telephone traffic is measured         1. With echo         2. By relative congestion         3. In terms of the grade of service         4. In erlangs

83. If the antenna diameter in a radar system is increased by a factor of 4, the maximum range will be increased by a factor of:         1. Ã-2          b. 2          c. 4               d. 8

84. A high PRF will (indicate the false statement)         1. Make the returned echoes easier to distinguish from noise         2. Make target tracking easier with conical scanning         3. Increase the maximum range         4. Have no effect on the range resolution

85. The bandwidth of a radar receiver is inversely proportional to the         1. Pulse width         2. Pulse repetition frequency         3. Pulse interval         4. Square root of the peak transmitted power

86. If d is the pulse width, T is pulse repetition period and P is the peak power, the duty ratio is         1. T/d b.P/T c.P/d d.d/T

87. If d is the duty ratio and P is the peak power in a pulsed transmitter, then the average power is         1. P.d          b. P.2d           c.P/d             d. P/2d

88. If the return echo arrives after the allocated pulse interval         1. It will interfere with operation of the transmitter         2. The receive might be overloaded         3. It will not be received         4. The target will appear closer than it really is

89. If the target cross section is changing, the best system for accurate angle traking is         1. Lobe switching

         2. Sequential lobing         3. Conical scanning         4. Monopulse

90. After a target has been acquired the best scanning system for tracking is         1. Nodding         2. Spiral         3. Conical         4. Helical

91. The Doppler frequency increases as the target         1. Approaches the radar         2. Recedes the radar         3. Moves perpendicular to the beam         4. Does not depend on the target velocity

92. The Doppler effect is used in (indicate the false statement)         1. Moving target plotting on the PPI         2. MTI system         3. FM Radar         4. CW Radar

93. Solution to the blind speed problem is to         1. Change the Doppler frequency         2. Vary the PRF         3. Use monopulse         4. Use MTI

94. The A-scope displays         1. Target position and range         2. Target range but not position         3. Target position but not range         4. Neither range nor position but only velocity

95. In the colour television system the sub carrier frequency in MHz is approximately         1. 3.58        b.4.5           c. 45.75           d. 5.58

96. In television 4: 3 : represents         1. The interlace ratio         2. The maximum horizontal deflection         3. Aspect ratio         4. The ratio of the two diagonals of picture tube

97. Equalizing pulses in TV are sent during the:         1. Horizontal blanking         2. Vertical blanking         3. The serrations         4. Horizontal retrace

98. The number of lines per field in Indian television system is:         1. 625          b. 312.5        c. 525           d. 262.5

99. The number of frames in Indian TV system is:         1. 50     b. 60       c. 25       d.30

100. In a TV receiver the colour killer:         1. Cuts off the chromastages during monochrome reception         2. Ensures that no colour is transmitted to monochrome receivers         3. Prevents colour overloading         4. Makes sure that the colour burst is not mistaken for sync pulses

Answer:-

1.      a

2.      c

3.      b

4.      c

5.      b

6.      b

7.      d

8.      c

9.      c

10.  d

11.  c

12.  d

13.  d

14.  a

15.  c

16.  d

17.  b

18.  c

19.  a

20.  b

21.  c

22.  b

23.  b

24.  c

25.  b

26.  c

27.  c

28.  c

29.  b

30.  c

31.  d

32.  b

33.  c

34.  b

35.  b

36.  d

37.  b

38.  a

39.  a

40.  a

41.  c

42.  a

43.  b

44.  c

45.  c

46.  d

47.  d

48.  b

49.  b

50.  d

51.  a

52.  d

53.  d

54.  a

55.  b

56.  a

57.  c

58.  b

59.  a

60.  b

61.  c

62.  a

63.  a

64.  b

65.  a

66.  b

67.  c

68.  a

69.  d

70.  b

71.  d

72.  b

73.  d

74.  b

75.  b

76.  c

77.  a

78.  b

79.  b

80.  d

81.  d

82.  a

83.  c

84.  c

85.  a

86.  d

87.  a

88.  d

89.  d

90.  c

91.  a

92.  a

93.  b

94.  b

95.  a

96.  c

97.  b

98.  b

99.  a

100.a

Paper: BEL Placement Paper (Technical-Electronics Ist)

  1. The gray code equivalent of binary 1100 is

a.       1011    b.  1101      c.  1010    d.  1100

   2. A Multiplexer has

a.       Multiple inputs and single output

b.      Single input and Multiple outputs

c.       Multiple inputs and Multiple outputs

d.      Multiple inputs for Storage of Data

   3. A binary half adder

a.       Adds two binary digits and produces their sum and carry

b.      Adds half the sum to the carry

c.       Adds two binary digits and carry from previous addition

d.      Adds two binary digits at half the speed

   4. An index register in a computer is for

a.       Arithmetic and logic functions

b.      Storage of results

c.       Modifying the address

d.      Counting the no of programmes

   5. An example of volatile memory is

a.       RAM     b.  ROM     c.  EPROM    d.  Magnetic tape

   6. Barrier voltage in a P-N junction is caused by

a.       Thermally generated electrons and holes

b.      Diffusion of majority carriers across the junction

c.       Migration of minority carriers across the junction

d.      Flow of drift current

   7. The temperature coefficient of an intrinsic semiconductor is

a.       Positive  b. Negative  c. Zero   d. Like metals

   8. A silicon transistor has a leakage current 1cbo = 1 ma. If the temp. rises by 50o C the leakage current will be

a.       30 ma   b.  32ma      c.  50ma       d.  no change

   9. The noise figure of an ideal amplifier in decibel is

a.       0.5       b.  0        c.  1         d.  10

  10. The rise time of an amplifier is 200 nsec. Its bandwidth is

a.       70MHz        b.  140MHz      c.  100MHz       d.  1.75Mhz

  11. MOSFET operates in

a.       Depletion mode only

b.      Enhancement mode only

c.       Depletion and enhancement mode

d.      None of these of the above

  12. A device which behaves like SCRs is

a.       UJT    b. Triac       c.  MOSFET    d.  SRD

  13. A plate modulated class C RF amplifier produces 100 KW of   radiated power at 100 % modulation. The modulating audio amplifier supplies approximately

a.       25KW    b.  33KW    c.  50KW     d.  66KW

  14. A 100 MHz   FM carrier, modulated by a 5 KHz sine wave deviates by 50 KHz

      If the frequency of the modulating sine wave is doubled, the deviation will

a.       Double          b. Half      c.  Quadruple    d.  Have no change

  15. Noise generated by a resistor is dependent on

a.       Its Value

b.      Its temperature

c.       Both value and temp

d.      None of these

  16. A 32 channel 8 bit PCM system samples at 8 KHz rate. The overall bit rate in kilobits per second will be

a.       2048      b.  2000    c.  1920    d.  64

  17. Stub matching eliminates standing wave on

a.       Load side of the stub

b.      Source side of the stub

c.       Both sides

d.      On the stub

  18. A half wave folded dipole has a radiation resistance of

a.       72 W   b.50W    c.  144W   d.  288W

  19. Top loading is used in antennas for

a.       Decrease in impedance

b.      Increase in bandwidth

c.       Increase in effective height

d.      Decease the height

  20. The term critical frequency in Ionospheric propagation is

a.       Lowest frequency reflected by Ionosphere

b.      Highest frequency reflected by the Ionosphere at vertical incidence

c.       Lowest frequency reflected by the Ionosphere at vertical incidence

d.      Lowest communication frequency possible

  21. The cathode ray oscilloscope can be used to measure

a.       Frequency    b.  Time interval    c.  Voltage   d.  All the above

  22. A wein bridge is used for measurement of

a.       Resistance   b.  Capacitance   c. Inductance   d.  Audio frequency

  23. The frame rate per second used in India TV is

a.       60    b. 50   c. 25   d.  30

  24. VHF signals are propagated

a.       Via the ionosphere

b.      Along the ground

c.       Through the troposphere

d.      By reflection in ionosphere

  25. The impedance of a 3 element yagi antenna is around

a.       75W     b.  300W     c.  50W     d.  100W

  26. A PIN diode is microwave

a.       Oscillator     b. Mixer   c.  Detector    d.  Switch

  27. A transmission line of VSWR 2 has a reflection coefficient

a.       0.25           b.  0.5           c.  75            d.  0

  28. Microwave repeaters are typically

a.       25   b.  50   c.  75      d.  100 Kms apart

  29. To overcome fading in a ship-to-ship communication system we can efficiently use

a.       Broadband Antenna

b.      Directional Antenna

c.       Space Diversity

d.      Frequency Diversity

  30. Frequency in the UHF range is propagate by waves of

a.       Ground     b. sky    c. Space   d.  Surface

  31. A duplexer is used to

a.       Receive two signals in one antenna

b.      Prevent interference between two antenna

c.       Mix two signals to the same antenna

d.      Allow one antenna for both transmission and reception

  32. Strapping is used in a magnetron to

a.       Prevent mode jumping

b.      Reduce frequency drift

c.       Ensure proper bunching

d.      Dissipate heat

  33. A rectangular waveguide behaves like a filter of

a.       Band pass   b. High pass    c. Low pass     d. Band stop

  34. The signal propagation time in milliseconds for a geosynchronous satellite is

a.       540    b.  270   c. 135   d. 100

  35. The silicon solar cell is a

a.       Photo conductive

b.      Photo emissive

c.       Photo voltaic

d.      Photo resistive

  36. For the national TV and ratio network, INSAT-IB uses

a.       400MHz     b. 2.5GHz     c. 2.5 and 5GHz       d.  4 and 6 GHz

  37. A typical fibre-optic detector is

a.       Step recovery diode

b.      Light emitting diode

c.       Avalanche photo diode

d.      Field effect transistor

  38. A modem is a device used for

a.       Digitizing voice  data

b.      Transmission of data on lines

c.       Modulating and demodulating signals sent on a line

d.      Suppressing noise interference

  39. The most effective anti-jamming technique is

a.       Frequency hopping

b.      Spread Spectrum

c.       Frequency synthesis

d.      Burst transmission

  40. Mono-mode is a term used in

a.       Fibre-optics

b.      Radar

c.       Satellite communication

d.      Magnetics

  41. Monopulse technique is used in

a.       Radar

b.      Radio relay

c.       Data communication

d.      Fibre-optics

  42. HDLC is a term for

a.       Data communication protocol

b.      Synchronizing pulses

c.       Gain control in receivers

d.      Error checking

  43. A gateway

a.       Is a place where radars are connected

b.      Permits dissimilar networks to communicate

c.       Bifurcates the RF path of a transmitter

d.      Is a feeder cable

  44. Ethernet is a name of

a.       Medium of computer communication

b.      Network for computer communication

c.       Procedures for computer communication network

d.      Software for computer communication

  45. If  several stations in a network want to use a single channel without interfering with one another, the technique used is called

a.       Carrier sense

b.      Phantom-freeze

c.       Packet switching

d.      Multiplexing

  46. In a monolithic IC, resistors are formed from

a.       Ceramic materials

b.      Copper

c.       P-type semiconductor

d.      Aluminium deposition

  47. ICs made by sputtering of materials on a ceramic substrate are called

a.       Monolithic    b. Hybrid    c. Thick film    d. Thin film

  48. Two coils (inductors) connected in series have a combined inductance of 15mH. When terminals of one of the coils are reversed and connected to the other, the combined inductance is measured to be 9mH. What is the value of mutual inductance

a.       1.5mH    b.3mH    c.6mH     d.12mH

  49. If a parallel LC circuit is excited at frequency less than its resonant frequency, the nature of its effective impedance is

a.       Resistive     b. Inductive     c. Capacitive    d. None of these of these

  50. The wave length of 1 Giga hertz frequency signal is

a.       10cm    b.  30cm     c. 3cm     d. 1cm

  51. Which of the following microwave tubes can be considered as broad band devices

a.       Magnetrons

b.      Klystrons

c.       Reflex klystrons

d.      Traveling wave tubes[TWT]

  52. Which family of the following integrated circuits has the highest speed

a.       DTL   b. ECL    c. TTL   d.CMOS

  53. The most important feature of CMOS family of ICs is

a.       High speed

b.      Small size

c.       Low power consumption

d.      Low input impedance

  54. What is the resolution of 8 bit A/D converter if its full scale voltage is 10v

a.       0.02v   b.  0.01     c. 0.039v      d. 0.078v

  55. What value of resistance is to be used in LSB of 4 bit weighted ladder D/A converter if MSB has 10 kW resistor

a.       160k   b. 80k   c. 240k  d. 100k

  56. The pulse width of a radar transmitter is 0.6m sec. and the pulse repetition rate is 700 Hz. The average power measured is 420 watts. What is the peak power

a.       100KW      b. 420KW      c. 1MW     d. None of these

  57. The device used for isolating the transmitter and receiver in a radar system is called

a.       Diplexer

b.      Duplexer

c.       Directional coupler

d.      None of these

  58. "Baud i� s

a.       Total No. of bits/sec in each character

b.      Reciprocal of shortest signal element in a character

c.       Duration of a character in data transmission

d.      None of these

  59. The advantage of Totem pole output stage in TTL ICs is

a.       Low output impedance

b.      Can sink more current

c.       Oscillations avoided

d.      None of these

  60. The capacitance value of a varactor is controlled by

a.       A reverse voltage applied to it

b.      A series resistance

c.       Varying its supply voltage

d.      Current through the device

  61. Electron volt is equivalent to

a.       3.8 * 10-20  erg

b.      1.602 * 10-12  erg

c.       1.602 * 10-18 erg

d.      1.602 * 10-16  erg

  62. The kinetic energy of photo electrons emitted by a photo sensitive surface depends on

a.       Intensity of the incident radiation

b.      Wavelength of the incident radiation

c.       Angle of incident of radiation

d.      Surface conditions of the surface

  63. Flux is expressed in radio-metric system in

a.       Lumens

b.      Photons

c.       Watts

d.      Candles

  64. In a three-phase bridge rectifier circuit, the ripple frequency is

a.       Same as line frequency

b.      Twice the line frequency

c.       Thrice the line frequency

d.      Six times the line frequency

  65. Energy stored in a capacitor as a function of voltage is given by

a.       CV2 

b.      1V2/2C

c.       ½ CV2

d.      1V/2C

  66. The operational amplifier used in analog computers have usually open loop flat gain approximately upto

a.       1MHz       b. 100MHz        c.  10MHz      d. 0.1MHz

  67. An oscillator of 350 MHz is fed with a pulse of rise time 2 n sec. The rise time of the displayed waveform is approximately

a.       1 n sec    b. 2.2 n sec     c. 2.0 n sec    d. 1.7 n sec

  68. A radar transmits a peak power of 100 KW with pulse width of 1 m sec and a pulse repetition rate of 100 KHz. The average output power of the radar is

a.       100KW   b.10KW    c. 1000KW       d. 50KW

  69. The incremental inductance in a coil is due to

a.       Saturation

b.      Superimposed DC

c.       Mutual inductance

d.      Change of frequency

  70. Microwave tube based on velocity modulation principle is

a.       Klystron

b.      Magnetron

c.       Light house tube

d.      Traveling wave tube

  71. Noise output from the receiver decreases uniformly with noise side band frequency for

a.       Frequency modulation

b.      Amplitude modulation

c.       Pulse amplitude modulation

d.      None of these

  72. In amplitude modulation the maximum permissible modulation index is

a.       Unity      b.  100   c.  infinity      d. None of these

  73. In frequency modulation the maximum permissible modulation index is

a.       Unity      b. 50      c.1000       d. no limit

  74. In FM  transmission and reception, the pre-emphasis and de-emphasis are used to improve the

a.       Signal to noise ratio

b.      Frequency response of the receiver

c.       Frequency response of the transmitter

d.      The sensitivity of the transmitter

  75. De-emphasis network uses the combination of

a.       R-L     b.  R-C      c.  R-L-C       d. Transformer

  76. The usage of micro sec for defining emphasis is a standard practice but this micro sec definition means

a.       3 dB point of the network means

b.      mid point of the network response

c.       roll off the network response

d.      the stop band ripple of the network response

  77. Delayed  AGC is applied

a.       For all singal strength

b.      For singal strength exceeding a specified limit

c.       For low singal strength

d.      For FM receiver

  78. Selectivity means

a.       Bandwidth

b.      Gain

c.       Modulation index

d.      None of these

  79. Narrow bandwidth broadcast reduces

a.       The quality and noise

b.      Quality alone

c.       Noise alone

d.      Quality and intelligibility

  80. Squelch means keeping the receiver

a.       ON in the absence of carrier

b.      OFF in the absence of carrier

c.       To remove AGC

d.      Increase the AGC

  81. Let Z be the series impedance and Y be the shunt admittance of the transmission line, then the characteristic impedance

a.       Ã-ZY      b.Ã-Y/Z       c. Ã-Z/Y         d.All the above

  82. Noise figure of an amplifier is defined as

a.       Input SNR output SNR

b.      Input SNR / output SNR

c.       Output SNR / input SNR

d.      Input SNR / gain

  83. A broadcast radio transmitter radiates 10 KW power when modulation is 60%. Its carrier power will be

a.       8.47KW    b.8.92KW    c. 8.31KW   d.10.00KW

  84. In AM transmission antenna current is 8 Ampere at zero modulation indexes but increased to 8.93 Ampere when modulated on single sine wave. Then the % of modulation is approximately

a.       70.1%     b. 80.1%   c. 65.1%    d. 10.0%

  85. In AM transmission antenna current is 8 Ampere at zero modulation index. At 80% modulation index the antenna current will be

a.       10.00A     b.  8.72A       c.   9.19A      d.  9.79A

  86. If two sine waves are amplitude modulated with modulation index m1 and m2, the effective modulation index is

a.       Ã- m12/m22

b.      Ã- m1 m2

c.       Ã- m12+m22

d.      Ã- m22/m12

  87. If it is transmitted current and Ic is transmitter current at zero modulation index and the transmitted current at modulation index of m will

a.       It = Ic Ã-[1+m]

b.      It = Ic Ã-[1+m2]

c.       It = Ic Ã-[1+m/22]

d.      It = IcÃ-1+m2

  88. If Rr is the radiation resistance and Rd is the lumped resistance, then the antenna efficiency is given as "

a.       (Rr - Rd) / (Rr + Rd)

b.      (Rr + Rd) / (Rr " Rd)

c.       Rr / (Rr + Rd)

d.      Rd / (Rr + Rd)

  89. In end fire array, the current

a.       Magnitude and phase in each element is the same

b.      Magnitude is the same but phase is different in each element

c.       Magnitude is different but no phase difference in each element

d.      Magnitude and phase are different in each element

  90. In a board side array, the current

a.       Magnitude and phase in each element is the same

b.      Magnitude is the same but phase is different

c.       Magnitude is different but no phase difference in each element

d.       Magnitude and phase are different in each element

  91. Beam width of the 2 metre paraboloid reflector at 6 GHz is

a.       4.5o

b.      9.25o

c.       3.5o

d.      7.75o

  92. The cut of wave length for TE m, n mode is in a wave guide of dimension a*b is

a.       2/Ã-(m/a)2 +(n/b)2

b.      2Ã- [m/a]2 + [n/b]2

c.       Ã-(m/a)2 + (n/b)2 /2

d.      Ã- [m/a]2 + [n/b]2

  93. For the standard rectangular waveguide dimension of 4*2 cm the off wavelength for TM11 mode is approximately

a.       1.788cm     b.  3.576cm      c.  1.682cm      d.  2.546cm

  94. In IMPATT diode, the voltage and current are

a.       In phase

b.      Out off phase by 90o

c.       Out off phase by 180o

d.      None of these of the above

  95. Which of the following statement is true

a.       Tunnel diode & IMPATT diode are negative resistance devices

b.      Tunnel diode is positive resistance device and the IMPATT diode is negative resistance device

c.       Tunnel diode is negative resistance device and the IMPATT diode is positive resistance device

d.      None of these of the above

  96. In a SSB modulation system with 100% modulation index the power saving will be

a.       5/6 of carrier power

b.      2/8 of carrier power

c.       5/12 of the carrier power

d.      ½ of the carrier power

  97. In SSB modulation the modulation index is increased from 0.5 to 1.0, then the power will be increased by

a.       2 times  b. 4 times     c. 16 times      d. 32 times

  98. 900 rpm is equal to

a.       94.2 rad/sec

b.      47.1 rad/sec

c.       188.4 rad/sec

d.      16.72 rad/sec

  99. Darlington pair is used to

a.       Increase the voltage gain

b.      Increase the current gain

c.       Decrease voltage gain

d.      Decrease current gain

 100. The transfer function of the system shown is

a.       G(s) / {1 + H(s)}

b.      G(s) H(s) / {1 + G(s) H(s)}

c.       G(s) / {1 + G(s) H(s)}              d. G(s) / G(s) H(s)

Electronics-I   Answers

1.      c

2.      a

3.      a

4.      c

5.      a

6.      b

7.      b

8.      b

9.      b

10.  d

11.  c

12.  b

13.  b

14.  d

15.  c

16.  a

17.  c

18.  d

19.  c

20.  b

21.  d

22.  d

23.  c

24.  b

25.  b

26.  d

27.  c

28.  b

29.  d

30.  c

31.  d

32.  a

33.  b

34.  c

35.  c

36.  d

37.  c

38.  c

39.  a

40.  a

41.  a

42.  a

43.  b

44.  b

45.  d

46.  c

47.  d

48.  a

49.  b

50.  b

51.  d

52.  b

53.  c

54.  c

55.  b

56.  c

57.  b

58.  b

59.  a

60.  a

61.  b

62.  b

63.  a

64.  b

65.  c

66.  d

67.  c

68.  b

69.  d

70.  a

71.  a

72.  a

73.  b

74.  a

75.  b

76.  a

77.  b

78.  a

79.  a

80.  b

81.  c

82.  b

83.  a

84.  a

85.  c

86.  c

87.  c

88.  c

89.  b

90.  a

91.  c

92.  a

93.  b

94.  c

95.  a

96.  a

97.  b

98.  b

99.  b

100. C

BEL (Bharat Electronics Ltd) Paper Pattern on 19th September 2008Rated : +11 , -0

Pattern: BEL (Bharat Electronics Ltd) Paper Pattern on 19th September 2008

Part I---Objective questions (40 with 1.5 marks each) with 50% -ve marking1. Numerical problem based on modulation index fc, fm.......... (formula based direct queston).2.Poles & zeroes are at .01,1,20,100...... find phase margin/angle at f=50Hz. ans -90(By drawing bode plot)3.In n-type enhancement mode MOSFET drain current----------- options are- increase/decrease with inc/dec in drain/gate voltage. ans(d)4. Gain of an directional antenna 6db P=1mw find transmitted power.........(use Ptr= G * P.)5.Multiplication of two nos 10101010 & 10010011 in 2's complement form..6.A ckt is given suppplied with 15v with a series of resistance of 1k and a parallel combination of 12V zener diode and 2k resistance. FInd current through 2k resistance. ans: 6mA7.A MP has 16 line data bus & 12 line addr bus find memory range..........Ans..4K(4*1024bytes)8.Divide by 12 counter require minimum ..... no of flip flops Ans. 49.Storage time in p-n junction.10.Succesive approx. use in .... Ans ADC(analog to digital)11.Pre-emphasis require in ......... low freq/high freq signal.12.Handshake in MP ........... Ans to communicate with slower peripherals.13. Binary equivalent of 0.0625 Ans. 0.000114.Which code is self complement of itself15.Excess three code of an given binary no.16.When we add 6 in BCD operations....... Ans. if result exceed valid BCD nos.17.Shottky diode has better switching capability because it switch between.......18.Figure of Merit is same as......19.Swithcing in diode happens when....20.During forward bias majority charge conc. in depletion layers inc/decrease.....21.Channel capacity depend on....... Ans. Usable frequency or bandwidth22.A 2kHz signal is passed through an Low pass filter having cut-off freq 800Hz o/p will be23. Carrier amplitude 1v, peak to peak message signal 3mv find modulation index.

24.A 12V signal is quantized into two V/14 & 6 equal V/7 determine quantization error.

Part II True & false......(10 1 mark each) with 50% -ve marking1.Power dissipation in ECL is minimum.......... False2.Fourier Transform of a symmetric conjugate function is always real .... True3.Divide by 12 counter requires a minimum of 4 flip flops.......True4.Boron can be use as impurity to analyse base of a npn transistor.......True

In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much1.  Look at this series: 2, 1, (1/2), (1/4), ... What number should come next?

A. (1/3) B. (1/8)

C. (2/8) D. (1/16)

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2.  Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?

A. 7 B. 10

C. 12 D. 13

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3.  Look at this series: 36, 34, 30, 28, 24, ... What number should come next?

A. 20 B. 22

C. 23 D. 26

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4.  Look at this series: 22, 21, 23, 22, 24, 23, ... What number should come next?

A. 22 B. 24

C. 25 D. 26

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5.  Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?

A. 12 B. 14

C. 27 D. 53

Look carefully for the pattern, and then choose which pair of numbers comes next.1.  28 25 5 21 18 5 14

A. 11 5 B. 10 7

C. 11 8 D. 5 10

E. 10 5

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2.  8 11 21 15 18 21 22

A. 25 18 B. 25 21

C. 25 29 D. 24 21

E. 22 26

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3.  9 16 23 30 37 44 51

A. 59 66 B. 56 62

C. 58 66 D. 58 65

E. 54 61

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4.  2 8 14 20 26 32 38

A. 2 46 B. 44 50

C. 42 48 D. 40 42

E. 32 26

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5.  9 11 33 13 15 33 17

A. 19 33 B. 33 35

C. 33 19 D. 15 33

E. 19 21

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Look carefully for the pattern, and then choose which pair of numbers comes next.1.  42 40 38 35 33 31 28

A. 25 22 B. 26 23

C. 26 24 D. 25 23

E. 26 22

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2.  6 10 14 18 22 26 30

A. 36 40 B. 33 37

C. 38 42 D. 34 36

E. 34 38

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3.  8 12 9 13 10 14 11

A. 14 11 B. 15 12

C. 8 15 D. 15 19

E. 8 5

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4.  36 31 29 24 22 17 15

A. 13 11 B. 10 5

C. 13 8 D. 12 7

E. 10 8

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5.  3 5 35 10 12 35 17

A. 22 35 B. 35 19

C. 19 35 D. 19 24

E. 22 24

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Find the number that fits somewhere into the middle of the series. Some of the items involve both numbers and letters1.  Look at this series: F2, __, D8, C16, B32, ... What number should fill the blank?

A. A16 B. G4

C. E4 D. E3

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2.  Look at this series: 664, 332, 340, 170, ____, 89, ... What number should fill the blank?

A. 85 B. 97

C. 109 D. 178

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3.  Look at this series: V, VIII, XI, XIV, __, XX, ... What number should fill the blank?

A. IX B. XXIII

C. XV D. XVII

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4.  Look at this series: 70, 71, 76, __, 81, 86, 70, 91, ... What number should fill the blank?

A. 70 B. 71

C. 80 D. 96

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5.  Look at this series: 8, 43, 11, 41, __, 39, 17, ... What number should fill in the blank?

A. 8 B. 14

C. 43 D. 44

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Find the number that fits somewhere into the middle of the series. Some of the items involve both numbers and letters6.  Look at this series: VI, 10, V, 11, __, 12, III, ... What number should fill the blank?

A. II B. IV

C. IX D. 14

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7.  Look at this series: (1/9), (1/3), 1, ____ , 9, ... What number should fill the blank?

A. (2/3) B. 3

C. 6 D. 27

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8.  Look at this series: 83, 73, 93, 63, __, 93, 43, ... What number should fill the blank?

A. 33 B. 53

C. 73 D. 93

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9.  Look at this series: 15, __, 27, 27, 39, 39, ... What number should fill the blank?

A. 51 B. 39

C. 23 D. 15

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10.  Look at this series: 72, 76, 73, 77, 74, __, 75, ... What number should fill the blank?

A. 70 B. 71

C. 75 D. 78

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Find the number that fits somewhere into the middle of the series. Some of the items involve both numbers and letters11.  Look at this series: J14, L16, __, P20, R22, ... What number should fill the blank?

A. S24 B. N18

C. M18 D. T24

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12.  Look at this series: 4, 7, 25, 10, __, 20, 16, 19, ... What number should fill the blank?

A. 13 B. 15

C. 20 D. 28

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13.  Look at this series: XXIV, XX, __, XII, VIII, ... What number should fill the blank?

A. XXII B. XIII

C. XVI D. IV

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14.  Look at this series: 0.15, 0.3, ____, 1.2, 2.4, ... What number should fill the blank?

A. 4.8 B. 0.006

C. 0.6 D. 0.9

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15.  Look at this series: U32, V29, __, X23, Y20, ... What number should fill the blank?

A. W26 B. W17

C. Z17 D. Z26

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In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much6.  Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?

A. 14 B. 15

C. 21 D. 23

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7.  Look at this series: 58, 52, 46, 40, 34, ... What number should come next?

A. 26 B. 28

C. 30 D. 32

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8.  Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?

A. 7 B. 10

C. 14 D. 15

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9.  Look at this series: 8, 22, 8, 28, 8, ... What number should come next?

A. 9 B. 29

C. 32 D. 34

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10.  Look at this series: 31, 29, 24, 22, 17, ... What number should come next?

A. 15 B. 14

C. 13 D. 12

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In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much6.  Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?

A. 14 B. 15

C. 21 D. 23

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7.  Look at this series: 58, 52, 46, 40, 34, ... What number should come next?

A. 26 B. 28

C. 30 D. 32

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8.  Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?

A. 7 B. 10

C. 14 D. 15

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9.  Look at this series: 8, 22, 8, 28, 8, ... What number should come next?

A. 9 B. 29

C. 32 D. 34

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10.  Look at this series: 31, 29, 24, 22, 17, ... What number should come next?

A. 15 B. 14

C. 13 D. 12

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In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much11.  Look at this series: 1.5, 2.3, 3.1, 3.9, ... What number should come next?

A. 4.2 B. 4.4

C. 4.7 D. 5.1

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12.  Look at this series: 14, 28, 20, 40, 32, 64, ... What number should come next?

A. 52 B. 56

C. 96 D. 128

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13.  Look at this series: 2, 4, 6, 8, 10, ... What number should come next?

A. 11 B. 12

C. 13 D. 14

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14.  Look at this series: 201, 202, 204, 207, ... What number should come next?

A. 205 B. 208

C. 210 D. 211

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15.  Look at this series: 544, 509, 474, 439, ... What number should come next?

A. 404 B. 414

C. 420 D. 445

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In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much16.  Look at this series: 80, 10, 70, 15, 60, ... What number should come next?

A. 20 B. 25

C. 30 D. 50

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17.  Look at this series: 2, 6, 18, 54, ... What number should come next?

A. 108 B. 148

C. 162 D. 216

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18.  Look at this series: 5.2, 4.8, 4.4, 4, ... What number should come next?

A. 3 B. 3.3

C. 3.5 D. 3.6

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19.  Look at this series: 1000, 200, 40, ... What number should come next?

A. 8 B. 10

C. 15 D. 20

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Look carefully for the pattern, and then choose which pair of numbers comes next.6.  2 3 4 5 6 4 8

A. 9 10 B. 4 8

C. 10 4 D. 9 4

E. 8 9

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7.  17 17 34 20 20 31 23

A. 26 23 B. 34 20

C. 23 33 D. 27 28

E. 23 28

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8.  6 20 8 14 10 8 12

A. 14 10 B. 2 18

C. 4 12 D. 2 14

E. 14 14

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9.  21 25 18 29 33 18

A. 43 18 B. 41 44

C. 37 18 D. 37 41

E. 38 41

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10.  75 65 85 55 45 85 35

A. 25 15 B. 25 85

C. 35 25 D. 85 35

E. 25 75

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11.  11 16 21 26 31 36 41

A. 47 52 B. 46 52

C. 45 49 D. 46 51

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12.  3 8 13 18 23 28 33

A. 39 44 B. 38 44

C. 38 43 D. 37 42

E. 33 38

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13.  84 78 72 66 60 54 48

A. 44 34 B. 42 36

C. 42 32 D. 40 34

E. 38 32

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14.  20 20 17 17 14 14 11

A. 8 8 B. 11 11

C. 11 14 D. 8 9

E. 11 8

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15. 61 57 50 61 43 36 61

A. 29 61 B. 27 20

C. 31 61 D. 22 15

E. 29 22

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Directions to Solve

Look carefully for the pattern, and then choose which pair of numbers comes next.16. 9 12 11 14 13 16 15

A. 14 13 B. 18 21

C. 14 17 D. 12 13

E. 18 17

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17. 4 8 22 12 16 22 20 24

A. 28 32 B. 28 22

C. 22 28 D. 32 36

E. 22 26

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18. 40 40 31 31 22 22 13

A. 13 4 B. 13 5

C. 4 13 D. 9 4

E. 4 4

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19. 1 10 7 20 13 30 19

A. 26 40 B. 29 36

C. 40 25 D. 25 31

E. 40 50

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20. 10 20 25 35 40 50 55

A. 70 65 B. 60 70

C. 60 75 D. 60 65

E. 65 70

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Look carefully for the pattern, and then choose which pair of numbers comes next.6.  13 29 15 26 17 23 19

A. 21 23 B. 20 21

C. 20 17 D. 25 27

E. 22 20

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7.  14 14 26 26 38 38 50

A. 60 72 B. 50 62

C. 50 72 D. 62 62

E. 62 80

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8.  44 41 38 35 32 29 26

A. 24 21 B. 22 19

C. 23 19 D. 29 32

E. 23 20

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9.  34 30 26 22 18 14 10

A. 8 6 B. 6 4

C. 14 18 D. 6 2

E. 4 0

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10.  32 31 32 29 32 27 32

A. 25 32 B. 31 32

C. 29 32 D. 25 30

E. 29 30

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Look carefully for the pattern, and then choose which pair of numbers comes next.11.  7 9 66 12 14 66 17

A. 19 66 B. 66 19

C. 19 22 D. 20 66

E. 66 20

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12.  3 8 10 15 17 22 24

A. 26 28 B. 29 34

C. 29 31 D. 26 31

E. 26 32

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13.  4 7 26 10 13 20 16

A. 14 4 B. 14 17

C. 18 14 D. 19 13

E. 19 14

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14.  32 29 26 23 20 17 14

A. 11 8 B. 12 8

C. 11 7 D. 32 29

E. 10 9

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15.  16 26 56 36 46 68 56

A. 80 66 B. 64 82

C. 66 80 D. 78 68

E. 66 82

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Look carefully for the pattern, and then choose which pair of numbers comes next.16.  2 44 4 41 6 38 8

A. 10 12 B. 35 32

C. 34 9 D. 35 10

E. 10 52

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17.  17 32 19 29 21 26 23

A. 25 25 B. 20 22

C. 23 25 D. 25 22

E. 27 32

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18.  17 14 14 11 11 8 8

A. 8 5 B. 5 2

C. 8 2 D. 5 5

E. 5 8

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19.  10 34 12 31 14 28 16

A. 25 18 B. 30 13

C. 19 26 D. 18 20

E. 25 22

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20.  11 14 14 17 17 20 20

A. 23 23 B. 23 26

C. 21 24 D. 24 24

E. 24 27

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1. Numerical problem based on modulation index fc, fm………. (formula based direct

queston).

2.Poles & zeroes are at .01,1,20,100…… find phase margin/angle at f=50Hz. ans -

90(By drawing

bode plot)

3.In n-type enhancement mode MOSFET drain current———– options are-

increase/decrease with

inc/dec in drain/gate voltage. ans(d)

4. Gain of an directional antenna 6db P=1mw find transmitted power………(use Ptr= G *

P.)

5.Multiplication of two nos 10101010 & 10010011 in 2′s complement form..

6.A ckt is given suppplied with 15v with a series of resistance of 1k and a parallel

combination of 12V

zener diode and 2k resistance. FInd current through 2k resistance. ans: 6mA

7.A MP has 16 line data bus & 12 line addr bus find memory

range……….Ans..4K(4*1024bytes)

8.Divide by 12 counter require minimum ….. no of flip flops Ans. 4

9.Storage time in p-n junction.

10.Succesive approx. use in …. Ans ADC(analog to digital)

11.Pre-emphasis require in ……… low freq/high freq signal.

12.Handshake in MP ……….. Ans to communicate with slower peripherals.

13. Binary equivalent of 0.0625 Ans. 0.0001

14.Which code is self complement of itself

15.Excess three code of an given binary no.

16.When we add 6 in BCD operations……. Ans. if result exceed valid BCD nos.

17.Shottky diode has better switching capability because it switch between…….

18.Figure of Merit is same as……

19.Swithcing in diode happens when….

20.During forward bias majority charge conc. in depletion layers inc/decrease…..

21.Channel capacity depend on……. Ans. Usable frequency or bandwidth

22.A 2kHz signal is passed through an Low pass filter having cut-off freq 800Hz o/p will

be

23. Carrier amplitude 1v, peak to peak message signal 3mv find modulation index.

24.A 12V signal is quantized into two V/14 & 6 equal V/7 determine quantization error.

Part II True & false……(10 1 mark each) with 50% -ve marking

1.Power dissipation in ECL is minimum………. False

2.Fourier Transform of a symmetric conjugate function is always real …. True

3.Divide by 12 counter requires a minimum of 4 flip flops…….True

4.Boron can be use as impurity to analyse base of a npn transistor…….True