Subject: Signals & Systems.

1) Graphical representation of a signal in time domain is called [ ] a) Frequency spectrum b) Frequency c) Wave form d) None

2) Analog signals can be converted into discrete time signals by [ ] a) Sampling b) Coding c) Quantizing d) None

3) U(t-a) = 0 if [ ] a) t-a =0 b) t-a < 0 c) t-a >0 d) None

4) A signal is a power signal if [ ] a) E=0, P=0 b) P=finite, E= Infinite c) P=finite, E=finite d) P=infinite, E=infinite

5) The sum of two periodic signals is periodic only if the ratio of their respective periods T1/T2 is [ ] a) A Rational number b) An irrational Number c) A complex number d) A Real number

6) A system whose output depends on future inputs is a [ ] a) Static System b) Dynamic System c) Non Causal System d) b & c

7) y(t)= x2(t) is [ ] a) LTI system b) Non linear Time invariant system c) Linear and time varying system d) None

8) y(n)=x(n)u(n) is a [ ] a) Static, Linear b) Causal, Time invariant c) Both a & b d) None

9) If we approximate a function by its orthogonal function, the error will be [ ] a) Zero

b) Small c) Large d) None

10) In a set of signals, if no signal can be represented as a linear combination of the remaining signals then such signals are [ ] a) Linearly Independent b) Linearly Dependent c) Orthogonal d) Ortho normal

11) Fourier series applies to [ ] a) Only periodic signals b) Only aperiodic signals c) Both periodic and aperiodic d) None

12) For the existence of Fourier series Dirchilet’s conditions are [ ] a) Necessary b) Sufficient c) Necessary and Sufficient d) None 13) The net areas of sinusoids over complete periods are [ ] a) Finite b) Infinite c) zero d) None 14) In the Trigonometric Fourier series representation, the value A0 is [ ] a) RMS value b) Mean square value c) Peak value d) Average value 15) The TFS representation of a function with half wave symmetry consists of [ ] a) Cosine terms only b) Sine terms only c) Odd harmonics d) Even harmonics 16) The Exponential Fourier series coefficient Cn in terms of TFS is [ ] a) Cn=1/2 ( an+jbn)

b) Cn=1/2(an-jbn) c) Cn= (an-jbn)

d) Cn= (an+jbn) 17) Hilbert transform is a [ ] a) Low pass filter b) -900 filter

c) High pass filter. d) 1800 filter.

18) The Fourier transform of x(-t) is [ ] a) X(w) b) X(-w) c) X(1/w) d) –X(w) 19) The characteristics of an LTI system are completely characterized by its [ ]

a) Impulse response b) Step Response c) Transfer function d) None

20) The commutative property of convolution states that [ ] a) x(t)*h(t) = h(t)*x(t) b) x(t)*[h1(t)+h2(t)]=x(t)*h1(t) + x(t)*h2(t) c) x(t)*[h1(t)*h2(t)]=[x(t)*h1(t)]*h2(t) d) None. 21) For distortion less transmission, the phase response is [ ] a) Constant b) Linear c) Zero d) Non linear. 22) For distortion less transmission, the bandwidth of the system is [ ] a)Finite b) Infinite c) Zero d) Very small. 23) The time convolution theorem states that F[x1(t)*x2(t)]= [ ] a) X1(w)X2(w) b)X1(w)*X2(w) c) 1/2 (X1(w)X2(w) d) 1/2 [X1(w)*X2(w)] 24) The condition for orthogonality of two functions x1(t) and x2(t) in terms of correlation is [ ] a) R12( ) =Infinite b) R12( ) =zero c) R12( ) =1 d) None 25) The cross correlation of x1(t) and x2(t) is the same as the convolution of [ ] a) x1(t) and x2(-t) b) x1(t) and x2(t) c)x1(-t) and x2(t)

d) x1(-t) and x2(-t) 26) The FT of auto correlation is [ ] a) PSD b) ESD c) any of (a) or (b) d) None

27) The auto correlation is maximum at [ ] a) =0 b) =infinite d) None. 28) The process of converting a CT signal into DT signal is called [ ] a) ADC b)DAC c) Sampling. d) None. 29) The nyquist rate of a signal is [ ] a) fm/2 b) 2 fm

c) fm

d) fm* fm

30) Aliasing occurs when the signal is [ ] a) Over sampled b) Under sampled c) Critically sampled. d) None.

Answers 1. C 2. A 3. B 4. B 5. A 6. D 7. B 8. A 9. C 10. A 11. A 12. B 13. C 14. D 15. C 16. B 17. B 18. B 19. A 20. A 21. B 22. B 23. A 24. B ,25. A ,26. C ,27.A ,28.C ,29.B ,30.B

Blanks 1) Discrete time signals are ________ ___in time and _______________ in amplitude. 2) In case of _______________ signals, not all the sinusoidal are periodic. 3) Double integration of a unit step results in a unit _______________ function. 4) Double differentiation of Unit ramp results in a ____________________ function. 5) For an Odd signal x(-t) = _____________ for all ‘t’. 6) All the static systems are ______________ systems. 7) Two functions are orthogonal over an interval (t1,t2) if __________ 8) The spectrum of Fourier series is __________________ in nature. 9) Absolute convergence condition is a _____________ condition for the existence of Fourier

transform. 10) Impulses in the Fourier transform of periodic signal are located at the _______________

frequencies of the signals. 11) Hilbert transform does not change the ________________ of a signal. 12) The Fourier transform of a Unit impulse function is ___________. 13) The FT of e-atu(t) is _______________. 14) The FT of a signum function is ____________. 15) The FT of (t*x(t)) is ______________. 16) The FT of x1(t)*x2(t) is _______________________. 17) The area under the Fourier Transform is ___________________. 18) Inverse FT x(t) of X(w) is given by ____________________________. 19) The FT of rect(t/T) is ________________________________. 20) The Fourier Transform of a DC signal x(t)=A is _____________________________. 21) If h(t)=0 for t<0, the system is a ______________________ system. 22) If h(t) is the impulse response of the system and h1(t) is the impulse response of its inverse

system, then h(t)*h1(t)= ____________________. 23) For distortion less transmission, the magnitude |H(w)| must be ________________. 24) The bandwidth B and rise time tr are related as _______________________. 25) A signal x(t) is said to be transmitted without distortion, if the output y(t) = ________. 26) The cross correlation of ________________ signals is zero. 27) The auto correlation function and ESD form a ______________ pair. 28) Parsevals energy theorem states that ___________________________. 29) The distribution of average power of the signal in frequency domain is called ____________. 30) The total area under the PSD is equal to __________________ of the signal. 31) According to sampling theorem, the signal should be sampled at__________________. 32) Laplace transform is used to solve the _________________________ equations. 33) The graphical representation of pole and zero locations is called ___________________. 34) The ROC cannot contain any _____________. 35) If x(t) is a left sided signal, the ROC extends to the left of ___________ pole and no pole is

located in ___________. 36) 37) For a finite duration anti causal sequence the ROC is entire Z-plane except at ____________. 38) For a finite duration two sided sequence the ROC is entire Z-plane except at ____________. 39) The Z-transform converts ____________ equations into ________________ equations. 40) The range of values of Z for which the Z-transform converges is ___________.

SS Fill in the blanks answers: 1) Discrete & Continuous 2) DT 3) Parabolic 4) Impulse 5) –x(t) 6) Causal

7) 1( ) 2( ) = 0

8) Discrete 9) Sufficient 10) Harmonic 11) Domain 12) Unity 13) 1/(a+jw) 14) 2/jw

15) J X(w)

16) X1(w)X2(w) 17) x(0)

18) ( ) dw

19) sin(w /2) 20) A2 (w) 21) Causal 22) (t) 23) Constant 24) tr*B=constant 25) X(t-td) 26) Orthogonal 27) FT

28) E= | ( )|^2 dw

29) PSD 30) Average Power 31) Ws>2Wm 32) Differential 33) Pole-Zero plot 34) Poles 35) Leftmost, ROC 36) Exterior 37) Z=infinite. 38) Z=0 and z= infinite 39) Difference, Algebraic 40) ROC.

ELECTRONIC DEVICES AND CIRCUITS BITS

1.The Bandgap of silicon at 3000 is (A)1.36eV(B) 1.10eV(C) 0.80eV(D) 0.67eV

2. Drift current in the semiconductors depends upon (A) only the electric field (B) only the carrier concentration gradient (C) both the electric field and the carrier concentration (D) both the electric field and the carrier concentration gradient 3.A Zener diode, when used in voltage stabilization circuits, is biased in (A) reverse bias region below the breakdown voltage (B) reverse breakdown region (C) forward bias region (D) forward bias constant current mode 4.In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces (A) superior quality oxide with a higher growth rate (B) inferior quality oxide with a higher growth rate (C) inferior quality oxide with a lower growth rate (D) superior quality oxide with a lower growth rate 5. In a MOSFET operating in the saturation region, the channel length modulation effect causes (A) an increase in the gate-source capacitance (B) a decrease in the Transconductance (C) a decrease in the unity-gain cutoff frequency (D) a decrease in the output resistance 6. In the circuit shown below, the knee current of the ideal Zener diode is 10mA. To maintain 5V across L

R , the minimum value of L R in and the minimum power rating of the Zener diode in mW, respectively, are

(A) 125 and 125 (B) 125 and 250 (C) 250 and 125 (D) 250 and 250:

7 .In the circuit shown below, 1 Q has negligible collector-to-emitter saturation voltage and the diode drops negligible voltage across it under forward bias. If Vcc is 5V,X and Y are digital signals with 0 V as logic 0 and Vcc as logic 1, then the Boolean expression for Z is

(A) XY (B) X Y (C) X Y (D) X Y

8. A voltage 1000sin t Volts is applied across YZ. Assuming ideal diodes, the voltage measured across WX in Volts, is

(A) sin t

(B) sin t sin t / 2

(C) sin t sin t / 2 (D) 0 for all t

9.In the circuit shown below, the silicon npn transistor Q has a very high value of . The required value of R2 in k to produce IC 1mA is

(A) 20 (B) 30 (C) 40 (D) 50

10. A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10ºC, the forward bias voltage across the PN junction (A) increases by 60mV (B) decreases by 60mV (C) increases by 25mV (D) decreases by 25mV 11. In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7 V. The thermal voltage Vt kT / q 25mV. The small signal inputVi=Vp V cos t where V 100mV .

The bias current IDC through the diodes is (A) 1 mA (B) 1.28 mA (C) 1.5 mA (D) 2 mA

12. In the circuit what is y

13.

In the circuit shown Assuming VCE(sat)=0.2V and ß=50 the minimum base current required to operate the transistor in saturation region (A)56µA (B)140µA (c)60mA (d)3Ma 14. Calculate minority current ICO if IC = 20.002 mA and IC majority = 20 mA. A.20 A B. 0.002 A C. 2 nA

D.2 A

15. Use this table of collector characteristics to calculate ac at VCE = 15 V and IB = 30 A.

A.100 B. 106 C. 50 D.400

16. Determine the value of when = 100.

A.1.01 B. 101 C. 0.99

D.Cannot be solved with the information provided

17. Determine the peak value of the output waveform.

A.25 V B. 15 V C. –25 V D.–15 V

18. What is the peak inverse voltage across each diode in a voltage doubler? A.Vm B. 2Vm C. 0.5Vm D.0.25Vm

19. What is the logic function of this circuit?

A.Positive logic AND gate B. Positive logic OR gate C. Negative logic AND gate D.Negative logic OR gate

20. A diode conducts when it is forward-biased, and the anode is connected to the ________ through a limiting resistor. A.positive supply B. negative supply C. Cathode

D.Anode

21.Reverse breakdown is a condition in which a diode A.is subjected to a large reverse voltage. B. is reverse-biased and there is a small leakage current. C. has no current flowing at all. D.is heated up by large amounts of current in the forward direction.

22. The forward voltage across a conducting silicon diode is about A.0.3 V. B. 1.7 V. C. –0.7 V. D.0.7 V.

23. An amplifier has an Rin = 1.2 k . The coupling capacitor is 1 F. Determine the approximate lower cutoff frequency. A.133 Hz B. 1.33 kHz C. 13.3 kHz D.133 kHz

24. An amplifier has an input signal voltage of 0.054 mV. The output voltage is 12.5 V. The

voltage gain in dB is A.53.6 dB. B. 107.3 dB. C. 231 dB. D.116 dB.

25. In a multistage amplifier, the overall frequency response is determined by the

A.frequency response of each stage depending on the relationships of the critical frequencies.

B. frequency response of the first amplifier. C. frequency response of the last amplifier.

D.lower critical frequency of the first amplifier and the upper critical frequency of the final amplifier

26. Which transistor bias circuit provides good Q-point stability with a single-polarity supply voltage? A.base bias B. collector-feedback bias C. voltage-divider bias D.emitter bias

27.Ideally, for linear operation, a transistor should be biased so that the Q-point is A.near saturation. B. near cutoff. C. where IC is maximum. D.halfway between cutoff and saturation

28.What unit is used to represent the level of a diode forward current IF? A.pA B. nA C. A D.mA

29.What is the resistor value of an ideal diode in the region of conduction? A.0 B. 5 k C. Undefined D.Infinity

30.Calculate static resistance RD of a diode having ID = 30 mA and VD = 0.75 V. A.25 B. 40

C. 0.04 D.0.025

31. Which of the following elements is most frequently used for doping pure Ge or Si? A.Boron B. Gallium C. Indium D.All of the above

32. Which capacitance dominates in the forward-bias region? A.Diffusion B. Transition C. Depletion D.None of the above

1 B2 C3 B4 D5 D6 B7 B8 D9 C

10 D11 A12 A13 A14 D15 A16 c17 B18 B19 A20 A21 A22 D23 A24 B25 A26 C27 D28 D29 A30 A31 D32 A

ELECTRONIC CIRCUIT ANALYSIS BITS 1. With transformer connection to load the maximum efficiency of the class A amplifier will go up to maximum of [ ]

a. 78.5% b.25% c.50% d.66%

2. An oscillator of LC type having a split capacitor in the tank circuit is [ ] a. Hartley b. Colpitts c. Tuned d. Wein Bridge 3. The purpose of resonant circuits in tuned circuits is [ ] a. TO provide properly matching load impedance b. To reset unwanted harmonics c. To couple power to load d. All of the above 4. Which of the following combination can be used as a buffer_____ [ ] a. CE b. CB c. CC d. All 5. In voltage shunt feedback, the input impedance [ ] a. increases b. decreases c. depends on dc voltage applied d. depends on frequency of operation 6. The units of derating factor in power amplifier is [ ] a. Volts/

oC b. Watts/

oC c. Watts/ Cm

2 d. None

7. To reduce further harmonic distortion in large signal tuned amplifiers_______- is used [ ] a. feedback configuration b. transformer coupling c. Push Pull configuration d. all of the can be used 8. In a Crystal oscillator the frequency is very stable due to ___________ of the crystal [ ] a. Rigidity b. high Q c. vibration d. none 9. Source follower is a negative feedback amplifier using ________ feedback [ ] a. Voltage shunt b. current shunt c. voltage series d. current series 10. The linearity of a Class A Amplifier is __ [ ] a. poor b. fair c. good d. very good 11. Negative feedback in amplifier [ ] (a) improves SNR at the input (b) improves SNR at the output

(c) Increases distortion (d) None of the above 12. For generating a sinusoidal wave of 1KHz frequency, the most suitable oscillator is ____ [ ] (a) Hartley (b) Colpitts (c) Wien bridge (d) None of the above 13. The frequency stability of LC oscillator is _______ than RC oscillators. [ ] (a) less (b) more (c) either a or b (d) None of the above 14. The gain of an amplifier with feedback is ______. [ ]

- - 15. An important limitation of a crystal oscillator is ________. [ ] (a) its low output (b) its high Q (c) less availability of quartz crystal (d) its high output 16. In tuned amplifiers, harmonic distortion is ____________. [ ] (a) infinite (b) more (c) less (d) None 17. Double tuned amplifier provides ____ bandwidth than single tuned amplifiers. [ ] (a)larger (b) smaller (c) negligible (d)constant 18. Tuned amplifiers can be used in _____. [ ] (a)Radar (b)IF amplifiers (c) both a and b (d)None 19. In ____ power amplifier, the output signal varies for a full 360

0 of the cycle. [ ]

(a)Class A (b) Class B (c) Class AB (d) None of the above 20. Maximum theoretical efficiency of Class B push pull amplifier is ___. [ ] (a)25.5% (b) 50% (c) 75% (d) 78.5% 21.The disadvantage of negative feedback is [ ] (a)gain decreases (b)gain is always zero (c)gain is undefined (d)gain increases 22. With series feedback, (voltage or current), input resistance of an amplifier [ ] (a)decreases (b)increases (c)zero (d)infinity 23. Characteristics of an ideal voltage amplifier are: [ ]

(a)AV=infinity (b)Ri=infinity (c)Ro=0 (d)All the above

24. Oscillator circuits employ _______ type of feed back [ ] (a)positive (b)no feed back (c)negative (d)none 25. The coupling employed in amplifier circuits are [ ] (a)RC coupling (b)Transformer coupling (c)LC tuned coupling (d)All the above 26. In class B amplifiers relation between maximum power dissipation Pc and maximum output power dissipation Po is Pc= ____ Po [ ] (a)0.1 (b)0.2 (c)0.3 (d)0.4 27. Due to input signal swing, if the operating point shifts into cutoff and saturation regions, that amplifier is classified as _________ amplifier. [ ] (a)small signal (b)large signal (c)both a and b (d)not an amplifier 28. The application of Tuned amplifier is [ ] (a)radio signals (b)RF amplifier (c)Communication receivers (d)All the above 29. The purpose of resonant circuits in tuned circuits is [ ] (a)provide properly matching load impedance (b)reset unwanted harmonics (c)couple power to load (d)all the above 30. Double tuned amplifier provides _______ band width than single tuned amplifier. [ ] (a) smaller (b)larger (c)equal (d)zero

KEY FOR THE ABOVE BITS 1. C 2. B 3. D 4. C 5. B 6. B 7. C 8. C 9. B 10. D 11. b 12. c 13. a 14. a 15. a 16. c 17. a 18. c 19. a 20. d 21. a 22. b 23. d 24. c 25. d 26. d 27. b 28. d 29. d 30. b

1. Given that x y zˆ ˆ ˆr xa ya za is position vector of point (x, y, z) and r r . If n is an

integer, then the value of n.r r is

(A) nn 2 r (B) nn 3 r (C) nn 4 r (D) nn 5 r

2. Evaluate the divergence of the given vector at the point r=1/2 on x-axis, where

D = 2rˆ1/ r a (cylindrical).

(A) -8 (B) 8 (C) 7 (D) -7

3. The magnetic flux through each turn of 100 turns coil is 3t 2t mWb , where ‘t’ is in

seconds. The induced e.m.f at t = 2 sec is

(A) 1 V (B) – 1 V (C) 0-4 V (D) -0.4 V

4. The skin depth at 10 MHz for a conductor is 1cm. The phase velocity of an electromagnetic

wave, if the conductor is at 1000 MHz is

(A) 66 10 m / sec (B) 76 10 m / sec

(C) 83 10 m / sec (D) 86 10 m / sec

5. Region-1 (x<0), Region-2 (0<x<0.1) and Region-3 (x>0.1) have dielectric constants of 1, 2

and 3 respectively. If 1 x y zE 5a 5a 5a V / m , find 3E .

(A) x y z1.667a 5a 5a

(B) x y z5a 1.667a 5a

(C) x y z5a 5a 1.667a

(D) xl y z1.667a 5a 5a

6. If 310 S/ m , 0 , 0 and 6f 10 Hz , compute the propagation constant and

intrinsic impedance.

(A) 1 00.0533 j0.074 m ,86.548 35.78

(B) 1 00.0623 j0.079 m ,76.548 35.78

(C) 1 00.0728 j0.053 m ,86.548 35.78

(D) 1 00.0823 j0.079 m ,76.548 35.78

7. A circle loop of 10 cm radius is located in XY plane in a B-field given

by y zB 0.5 cos 377t 3a 4a T . Determine voltage induced in the loop.

(A) 33.69 sin377t V (B) 23.69cos 377t V

(C) 33.69cos 377t V (D) 23.69 sin377t V

8. If the electric field intensity of a uniform plane wave in air

is j5z j5zs x yE 20e a 25e a v / m , then SH is

(A) j5z j5zx y66.4e a 53.1e a mA / m

(B) j5z j5zx y66.4e a 53.1e a mA / m

(C) j5z j5zx y66.4e a 53.1e a mA / m

(D) j5z j5zx y66.4e a 53.1e a mA / m

9. A 5C point charge is located at origin in vacuum.

D at (0.3, 0.5,-0.4) is _______ ( 2C/ m ).

10. In a non magnetic medium, 9 9y zE 5cos 10 t 20x a 4sin 10 t 20x a xa V/m. The

dielectric constant of the medium is _______.

11. A short circuited line has 0in

jZZ3

. The length of the line is

(A) 8 (B) 6 (C) 12 (D) 41

12. The input impedance of the transmission line shown below is

(A) 2R0

(B) 0R 2 j 3

1 j2 3

(C) 0R2

(D) 01 jR1 j

inZ 0 0Z R

6

o2R

13. Which one of the following short circuited lines has the smallest input impedance?

(A) line2 (B) line4 (C) line8 (D) line6

14. A 50 distortion less transmission line has a capacitance of 1010 F / m . What is the

inductance per meter?

(A) 0.25 H (B) 500 H (C) 5000 H (D) 50 H

15. A transmission line of input impedance 900 through a quarter wavelength line is

terminated by a load of 25 . The quarter wave line characteristic impedance must be

(A) 40 (B) 150 (C) 400 (D) 420

16. The cut-off frequency of the dominant mode of a rectangular waveguide having aspect ratio

more than 2 is 10 GHz. The inner broad wall dimensions is given by

(A) 3 cm (B) 2 cm (C) 1.5 cm (D) 2.5 cm

17. In a waveguide, the evanescent modes are said to occur if

(A) The propagation constant is real

(B) The propagation constant is imaginary

(C) Only the TEM waves propagate

(D) The signal has a constant frequency

18. Match List-I (Dominant mode of propagation) with List-II (Type of Transmission structure)

and select the correct answer using the code given below the lists.

List I List II

P. Co-axial line 1. TE

Q. Rectangular waveguide 2. Quasi TEM

R. Micro strip line 3. Hybrid

S. Coplanar waveguide 4. TEM

(A) P-1, Q-4, R-2, S-3 (B) P-4, Q-1, R-3, S-2

(C) P-1, Q-4, R-3, S-2 (D) P-4, Q-1, R-2, S-3

19. A 10 km fiber with an attenuation constant of 0.2 dB/km serves as an optical link between

two cities. The power received is ______ %.

20. A step-index fiber has a core diameter of 80 m , a core refractive index of 1.62, and a

numerical aperture of 0.21.The refractive index of fibre at which the fiber can propagate at a

wavelength of 0.8 m is ________.

21. For a plane wave propagating in free space or two conductor transmission lines, what must be relationship among the phase velocity pv , the group velocity gv and speed of light (c)?

(A) p gv c v (B) p gv c v (C) p gv c v (D) p gv v c

22. A step-index fiber has a core diameter of 100 m, a core refractive index of 2.62, and a

numerical aperture of 0.21. Calculate the acceptance angle. (A) 11.11º (B) 12.12º (C) 13.13º (D) 14.14º 23. Light pulses propagate through a fiber cable with an attenuation of 0.25dB / km . Determine

the distance through which the power of pulses is reduced by 40%. (A) 2.746 km (B) 5.173 km (C) 8.874 km (D) 4.847 km 24. Which one of the following statements is not correct for a plane wave with

0.1x 6zˆH 0.5 e cos 10 t 2x a A / m ?

(A) The wave frequency is 106 rad/sec (B) The wave length is 3.14 m (C) The wave travels in +x direction (D) Wave is polarized in z direction 25. In an impedance smith chart, a clockwise movement along a constant resistance circle gives

rise to (A) A decrease in the value of reactance (B) An increase in the value of reactance (C) No change in the reactance value (D) No change in the impedance value 26. A transmission line of 100 characteristic impedance is terminated with 150 resistance.

The maximum impedance measured on the line is equal to (A) 150 (B) 250 (C) 300 (D) 350 27. Which of the following statements is/are true?

(1) If the wave is not following equiphase characteristics, then p

equivalence holds.

(2) In high loss medium, p and f are linearly related and can be termed as dispersion less media.

(A) Only (1) (B) Only (2) (C) Both (1) & (2) (D) None of these 28. Match List-I (parameters) with List-II (values) for a transmission line with a series impedance

Z= R j L m and a shunt admittance Y= G j C mJ .

List-I List-II

(P) Characteristic impedance oZ 1. ZY

(Q) Propagation constant 2. ZY

(R) The sending–end input impedance, Zs 3. YZ

when the line is terminated in its characteristic impedance oZ

Codes:

(A) P Q R3 1 1

(B) P Q R2 3 3

(C) P Q R2 1 2

(D) P Q R1 2 2

29. A step index fiber has a core diameter of 80 m , a core refractive index of 1.62, and a

numerical aperture of 0.21. The number of modes that the fiber can propagate at a wavelength of 0.8 m is _________.

30. A point charge of 5 nC is located at the origin. If V=2V at (0, 6, -8), then the potential at A (-3, 2, 6) is ______ (V).

31. A wave is propagating in Z-direction. The wave equation followed is 2

22

f r fz

where x y x yf E ,E ,H ,H . Given the medium is non homogenous, f will take the form

(A) rz1f f e (B) rz

2f f e (C) rz rz1 2f f e f e (D) All of these

32. Find the magnitude and direction of E at (6, 8,-3) in free space if a uniform line charge of

95 10 C/ m lies along z-axis.

(A) x y5.4a 7.2a V/ m (B) x y7.2a 5.4a V/ m (C) y z5.4a 7.2a V/ m (D) x z7.2a 5.4a V/ m

33. For a lossy media, intrinsic impedance is complex in nature and takes the form s SR jX ,

where sR and SX are given by

(A) ,2

(B) , (C) ,2

(D) ,2 2

34. Point charges of 94 10 C and 92 10 C are created in vacuum at points x = 2, x = 6 on X-axis respectively. Find E at (4, -1, 2) as unit vector.

(A) x y z4a 0.667a 1.332a V/ m (B) x y z0.937a 0.1562a 0.312a V/ m (C) x y z1.332a 0.667a 4a V/ m (D) x y z0.312a 0.937a 0.1562a V/ m

35. Assertion (A) : Magnetic field is continuous and always rotational. Reason (R) : H 0 and .H 0

(A) Both A and R are correct and R is the correct explanation of A (B) Both A and R are correct and R is not the correct explanation of A (C) A is true and R is false (D) A is false and R is true 36. Match the following: List-I List-II

(P) l SH.dl J.dsi 1. Faradays law

(Q) l SE.dl ( B / t).dsi 2. Amperes law

(R) vSv

D.ds dvi 3. Gauss law

(A) P-2, Q-3, R-1 (B) P-2, Q-1, R-3 (C) P-1, Q-2, R-3 (D) P-1, Q-3, R-2

37. Inconsistency in amperes law is made consistent by adding DJ term and is given by

c DH J J where CJ and DJ are conduction and displacement current densities. Then

DJ leads CJ by

(A) 090 (B) 045 (C) 0180 (D) 0

38. An electric wave propagating through a lossless medium 0 0, 81 is given by 8

yˆE 10cos 6 10 t x a V/ m , the phase constant is given by

(A) 9 rad / m (B) 12 rad / m (C) 18 rad / m (D) 24 rad / m

39. For a wave to be defined, it must have 1. An equiphase characteristic 2. Second order differential equation should be satisfied 3. Energy spectrum density should be constant Which of the following is true?

(A) 1 (B) 1, 2 (C) 1, 2, 3 (D) 2, 3

40. For a TEM wave propagating in two directions, the power density is given by Pr

(A) 2 2

x yz

E Ea (B)

2 2y z

x

E Ea

(C) 2 2

x zy

E E a (D) 2 2

x yz

E Ea

41. Assertion (A) : Polarization is always defined in terms of electric field

orientation.

Reason (R) : Magnetic field is due to induced effect of electric field so we cannot measure it directly.

(A) Both A and R are correct and R is the correct explanation of A (B) Both A and R are correct and R is not the correct explanation of A (C) A is true and R is false (D) A is false and R is true

42. Consider a wave which is having a phase velocity of 83 10 m / s . Find the group velocity and the medium in which it is travelling.

(A) 83 10 m / s , Free space (B) 82 10 m / s , Guided media

(C) 84 10 m / s , Guided media (D) 82 10 m / s , Free space

43. Phase velocity of a wave in a perfect dielectric with 0 0 rand is 0.4 times of its

value in the free space. The permeability r of the medium is _____________.

44. Phase difference between E and H in a high loss medium is ______________ (Degrees). 45. A plane wave 0 xE E cos( t z)a is incident on a good conductor whose current density at

the surface is 2

A5 z 0m

and skin depth is 4 m. The current density at 2 m from the

conductor surface is

(A) 220A / m (B) 1 j /2 25e A / m (C) 1/2 25e A / m (D) 0

46. Assertion (A) : For an oblique incidence on a dielectric interface in case of

perpendicular polarization, reflection and refraction components always exist.

Reason (R) : In perpendicular polarization, reflection coefficient become zero, when medium permittivities are same i.e., 2 1 and refraction component becomes zero when the incident wave grazes the interface. But both are impossible.

(A) Both A and R are correct and R is the correct explanation of A (B) Both A and R are correct and R is not the correct explanation of A (C) A is true and R is false (D) A is false and R is true 47. Assertion (A) : For the case of parallel polarization, a circular polarization

wave incident at Brewster’s angle becomes linearly polarized. Reason (R) : A wave composed of both parallel and perpendicular

components incident at Brewster angle produces a reflected wave with electric field components polarized parallel to the interface.

(A) Both A and R are correct and R is the correct explanation of A

(B) Both A and R are correct and R is not the correct explanation of A

(C) A is true and R is false

(D) A is false and R is true

48. For the case of parallel polarization for oblique incidence, a circular polarized wave is

elliptically polarized in medium 1 1 09 and linearly polarized in medium 2 2 04 for the angles of incidence equal to

(A) 1 19 2cos ,cos25 3

(B) 1 19 2sin ,sin25 3

(C) 1 12 9sin ,sin3 25

(D) 1 19 2tan , tan25 3

49. The emitted waves from an antenna of a radar with a ‘E’ field strength of 10,000 V/m hit a

target through the clutter whose MS61.7 .m The amount of electric field which is

incident on the target is ________________ ( / mJ ).

Assumption: The thickness of the clutter is negligible and f = 200 MHz

50. A shark in the water emits electromagnetic waves with xVE z, t 500cos t z am

. If

permittivity of water is 01.75 , then average power while crossing a circular creature with radius 2.5 m is _____________ (W).

51. Assertion (A) : Smith chart is designed for 2

length only.

Reason (R) : For every 2

length, the load impedance appears to be same as

Zin. (A) Both A and R are correct and R is the correct explanation of A (B) Both A and R are correct and R is not the correct explanation of A (C) A is true and R is false (D) A is false and R is true 52. Stub matching is used to match the load to characteristic impedance. Stub should be placed

such that the admittance value at that point is (A) 0 (B) jB (C) 1 j0 (D) 1 jB

53. A lossless transmission line is terminated with load impedance 50 j30 and the characteristic impedance of the line is 50 . The magnitude of reflection coefficient is

(A) 0.2 (B) 0.1 (C) 0.5 (D) 0.28 54. The characteristic impedance of any line is defined as (A) Geometric mean of its open and short circuited impedance (B) Line impedance having no reflection (C) Impedance looking into an infinite length of line (D) Both (A) & (C) 55. Match the following: List-I List-II

(P) Reflector (1) 2

Transmission line

(Q) Impedance inverter (2) 0jz tan l

(R) Short circuit impedance (3) 0jz cot l

(S) Open circuit impedance (4) 4

transmission line

(A) P-1, Q-2, R-3, S-4 (B) P-1, Q-4, R-2, S-3 (C) P-1, Q-4, R-3, S-2 (D) P-1, Q-3, R-4, S-2 56. In S-parameter matrix of order n×n, number of reflection coefficients and transmission coefficients respectively are (A) 2 2n , n n (B) 2n , n n 1 (C) n, n n 1 (D) n, n

57. Smith chart is a polar plot in which the following parameter is not expressed in terms of

normalized impedance. (A) Transmission coefficients (B) Reflection coefficient (C) Both (A) & (B) (D) None of these

58. Is the S - matrix of a transmission line given by1 00 0

possible?

(A) True (B) False (C) Can’t say (D) None of these 59. The characteristic impedance of a lossless transmission line at f 1GHz,L 1 ,C 1nF is

____________ (ohms).

60. The input impedance of an 4

open circuited transmission line is _______ (ohms).

61. The locus of the resistance 50 such that oZ 50 for constructing a smith chart is

(A) 2 2x y x 0 (B) 2 2x y 2x 2y 0

(C) 2 2x y 2x 2y 4 0 (D) No such locus exists

62. A distortion less transmission line has 0Z 50 , 10mNP / m, 0.167c (where

8c 3 10 m / s ), then R and L of transmission line are (A) 0.5 / m,100nH / m (B) 5 / m,1000nH / m (C) 50 / m,100nH / m (D) 500 / m,1000nH / m 63. Which of the following are true for a lossless transmission line?

1. inZ j ; for a shorted line with 4

l

2. in 0Z jZ ; for a open line with 2

l

3. in 0Z jZ ; for a shorted line with 4

l

4. in 0Z Z ; for a matched line of any length (A) 1 and 2 (B) 2 and 3 (C) 1 and 3 (D) 1 and 4 64. If PSWR is power standing wave ratio, then VSWR and PSWR corresponding to

00.5 45 is (A) 3, 9 (B) 2, 4 (C) 2+2j, 2–2j (D) 2, 2

65. Given that 0Z 600 , VSWR = 1.5, the distance at which first maximum occurs is 20cm from the load. If the operating frequency of the transmission line is 300 MHz, then the reflection coefficient is given by

(A) 00.2 45 (B) 00.2 53 (C) 00.2 144 (D) 00.2 164 66. For the transmission line shown below, the voltage which appears at the load after 1 sec

is _______________ (V).

Common Data Questions: 17 & 18

1 B 2 A 3 B 4 A 5 A 6 A 7 D

8 B 9 0.796 10 36 11 C 12 B 13 A 14 A

15 B 16 C 17 A 18 D 19 63.1 20 1.606 21 C

22 B 23 C 24 D 25 B 26 A 27 D 28 C

29 2176 30 3.929 31 C 32 A 33 D 34 A 35 A

36 B 37 A 38 C 39 C 40 A 41 A 42 A

43 6.25 44 45 45 B 46 A 47 D 48 B 49 0.268

50 8680 51 A 52 C 53 D 54 D 55 B 56 C

57 B 58 A 59 31.6 60 0 61 A 62 A 63 D

64 A 65 C 66 6.4

8V 200

100t=0

oZ 50

810 m /s

100m

PTSP OBJECTIVE QUESTIONS

1) P(S)= [ ]

a) 0 b) 1 c) d)-1

2) If A and B are mutually exclusive events then P(AUB)= [ ]

a)P(A)+P(B)-P(A B) b)P(A)+P(B)-P(AUB) c)P(A)+P(B) d)None

3) If A and B are Independent events P(A B)= [ ]

a)P(A)+P(B) b) P(A)P(B) c)P(A)+P(B) d) P(A)+P(B)-P(AUB)

4) A random variable maps each element of the sample space to a [ ]

a) Integer value b) Complex Value c) Real Value d)None

5) Mean of the binomial distribution is [ ]

a) N(1-P) b) NP c) NPq d)Nq

6) Mean of the uniform distribution is [ ]

a) (a+b)/2 b)a+b c)(a-b)/2 d) Cannot determine

7) Probability of getting at least one head when a coin is tossed for 3 times [ ]

a) 1/8 b)4/8 c) 6/8 d)7/8

8) Range of probability of event A is [ ]

a) 0 ( ) 1 b) -1 ( ) 1 c) - ( ) d) 0 ( )

9) An event with zero probability is called as [ ]

a) Uncertain event b) Certain event c) Cannot determine d) None

10) Received signal by the RADAR From the target follows ------ Distribution [ ]

a) Poisson b) Rayleigh c) Exponential d) gaussian

1 2 3 4 5 6 7 8 9 10

B C B C B A D A A C

ICA

1. What is the level of the output voltage of a ladder-network conversion? A.The analog output voltage proportional to the digital input voltage B. The digital output voltage proportional to the linear input voltage C. A fixed digital value Vref D.A fixed analog value Vref

2. Which of the following is not a linear/digital IC? A.Phase-locked loop B. Voltage-controlled oscillator C. Passive filter D.Comparator

3. A 339 IC is an example of a fourteen-pin DIP that can be made to function as a ________ A.comparator B. 555 timer C. D to A converter D.ladder network

4. What is the minimum number of conversions per second of a clock rate of 1 MHz operating a 10-stage counter in an ADC? A.1000 B. 976 C. 769 D.697

5. Which of the following is (are) the results of improvements built into a comparator IC? A.Faster switching between the two output levels B. Noise immunity C. Outputs capable of directly driving a variety of loads D.All of the above 6.

What is the first phase of the dual-slope method of conversion? A.Connecting the analog voltage to the integrator for a fixed time B. Setting the counter to zero C. Connecting the integrator to a reference voltage D.All of the above

7. On which of the following does the conversion depend in ladder-network conversion? A.Comparator B. Control logic C. Digital counter D.Clock

8.

Which of the following applications include a phase-locked loop (PLL) circuit? A.Modems B. Am decoders C. Tracking filters

D.All of the abovE

9. Determine the free-running frequency when R3 is set to 2.5 k .

A.19.7 kHz B. 32.5 kHz C. 116.39 kHz D.212.9 kHz

10. What is the functionality of the following circuit

A.ADC B. DAC C. comparator

D.555 timer

11. What is the function of a ladder network? A.Changing an analog signal to a digital signal B. Changing a linear signal to a digital signal C. Changing a digital signal to an analog signal

D.None of the above

12. Which of the slope intervals of the integrator does the counter in the analog-to-digital converter (ADC) operate? A.Positive B. Negative

C. Both positive and negative D.Neither positive nor negative

13. A 311 IC is an example of an eight-pin DIP that can be made to function as a ___ A.comparator B. 555 timer C. D to A converter D.ladder network

14. Determine the free-running frequency for this circuit.

A.32.5 kHz B. 53.33 kHz C. 533.3 kHz D.5.3 MHz

15. Which of the following best describes limitations for the 566 VCO? A.

B.

C. fo < 1 MHz D.All of the above

16. This circuit is an example of a ________.

A.comparator B. 555 timer C. D to A converter D.ladder network

17. Which of the following circuits is (are) linear/digital ICs? A.Comparators B. Timers C. Voltage-controlled oscillators D.All of the above

18. Which of the following best describes the output of a 566 voltage-controlled oscillator? A.Square-wave B. Triangular-wave C. Both square- and triangular-wave D.None of the above

19. Which of the following logic families has the highest maximum clock frequency? A.S-TTL B. AS-TTL

C. HS-TTL D.HCMOS

20. Logic circuits that are designated as buffers, drivers, or buffer/drivers are designed to have: A.a greater current/voltage capability than an ordinary logic circuit. B. greater input current/voltage capability than an ordinary logic circuit. C. a smaller output current/voltage capability than an ordinary logic.

D.greater input and output current/voltage capability than an ordinary logic circuit.

21. Which of the following logic families has the shortest propagation delay? A.S-TTL B. AS-TTL C. HS-TTL D.HCMOS

22. What causes low-power Schottky TTL to use less power than the 74XX series TTL? A.The Schottky-clamped transistor B. Nothing. The 74XX series uses less power. C. A larger value resistor D.Using NAND gates

23. What type of circuit is represented in the given figure, and which statement best describes its operation?

A.It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open

circuit—it is neither LOW nor HIGH.

B.

It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.

C. It is an active LOW buffer, which can be turned on and off by the ENABLE input. D.None of the above.

24. Which of the following logic families has the highest noise margin? A.TTL B. LS TTL C. CMOS D.HCMOS

25. Refer the given figure. Which of the following describes the operation of the circuit?

A.A LOW input turns Q1 and Q3 on; Q2 and Q4 are off. B. A LOW input turns Q1 and Q4 off; Q2 and Q3 are on. C. A HIGH input turns Q1, Q2, and Q3 off, and Q4 is on. D.A HIGH input turns Q1, Q2, and Q4 on; Q3 is off.

26. What type of logic circuit is shown below and what logic function is being performed?

A.It is an NMOS AND gate. B. It is a CMOS AND gate. C. It is a CMOS NOR gate. D.It is a PMOS NAND gate.

27. Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?

A.The device is an open-collector AND gate and requires both inputs to be HIGH in order to turn

the LED off. B. The device is a Schottky AND gate and requires only one low input to turn the LED off.

C.

The device is an open-collector AND gate and requires only one low input to turn the LED off.

D.The device is a Schottky open-collector AND gate and requires a low on both inputs to turn the LED off.

28. The nominal value of the dc supply voltage for TTL and CMOS is ________. A.+3 V B. +5 V

C. +9 V D.+12 V

29. Which is not an output state for tristate logic? A.HIGH B. LOW C. High-Z D.Low-Z

30. PMOS and NMOS circuits are used largely in ________. A.MSI functions B. LSI functions C. diode functions D.TTL functions

31. Calculate the output voltage for this circuit when V1 = 2.5 V and V2 = 2.25 V.

A.–5.25 V B. 2.5 V C. 2.25 V D.5.25 V

32. Calculate the output voltage if V1 = –0.2 V and V2 = 0 V.

A.0 V B. –6.6 V C. –4 V D.2 V

33. Determine the output voltage when V1 = –V2 = 1 V.

A.0 V B. –2 V C. 1 V D.2 V

34. Determine the output voltage for this circuit with a sinusoidal input of 2.5 mV.

A.–0.25 V

B. –0.125 V C. 0.25 V D.0.125 V

35. How many op-amps are required to implement this equation?

A.2 B. 3 C. 4 D.1 36. Calculate the cutoff frequencies of a bandpass filter with R1 = R2 = 5 k and C1 = C2 = 0.1microfarads A.fOL = 318.3 Hz, fOH = 318.3 Hz B. fOL = 636.6 Hz, fOH = 636.6 Hz C. fOL = 318.3 Hz, fOH = 636.6 Hz D.fOL = 636.6 Hz, fOH = 318.3 Hz

37. Determine the value of Rf (assuming that all have the same value).

A.500 k B. 50 k C. 25 k D.5 k

38. Calculate the input voltage for this circuit if Vo = –11 V.

A.1.1 V B. –1.1 V C. –1 V D.1 V

39. Calculate the output of the second stage op-amp if V1 = 25 mV.

A.–0.075 V B. 0.525 V C. 0.06 V D.4.2 V

40. Calculate the output voltage Vo if V1 = –V2 = 300 mV.

A.0 V B. –6 V C. 6 V D.–8 V

41. Calculate IL for this circuit.

A.3 mA B. 4 mA C. 5 mA D.6 mA

42. Calculate the cutoff frequency of a first-order low-pass filter for R1 = 2.5 k and C1 = 0.05 F.

A.1.273 kHz B. 12.73 kHz C. 127.3 kHz D.127.30 Hz

43. An example of an instrumentation circuit is a(n) ________ A.dc voltmeter B. display driver

C. ac voltmeter D.All of the above

44. Why differential amplifiers are preferred for instrumentation and industrial applications? a) Input resistance is low b) Produce amplified output c) Amplify individual input voltage d) Reject common mode voltage

45 . Which of the following is a combination of inverting and non-inverting amplifier? a) Differential amplifier with one op-amp b) Differential amplifier with two op-amps c) Differential amplifier with three op-amps d) Differential amplifier with four op-amps

46. The gain of differential amplifier with one op-amp is same as that of a) The inverting amplifier b) The non-inverting amplifier c) Both inverting and non-inverting amplifier d) None of the mentioned

47. Compute the output voltage if the input voltage is reduced to zero in differential amplifier with one op-amp? a) Inverted Voltage b) Same as the input voltage c) Amplified inverted voltage d) Cannot be determined

48. What is the net output voltage for differential amplifier with one op-amp a) Vo = -(RF /R1)*Vx b) Vo = -(RF /R1)*(Vx -Vy) c) Vo = (1+RF /R1)*(Vx -Vy) d) None of the mentioned

49. How many op-amps are required to implement this equation?

A.2 B. 3 C. 4 D.1

50. Determine the output voltage.

A.10(V2 – Vi) B. –10(V2 – V1) C. –10(V1 – V2) D.None of the above Keys

Q. No. Ans. Q. No. Ans. Q. No. Ans. Q. No. Ans. Q. No. Ans. 1 a 11 c 21 b 31 d 41 a 2 c 12 c 22 c 32 d 42 c

3 a 13 a 23 a 33 b 43 d 4 b 14 b 24 d 34 d 44 a 5 d 15 d 25 c 35 a 45 a 6 a 16 a 26 c 36 b 46 d

7 a 17 d 27 a 37 a 47 d 8 d 18 c 28 b 38 a 48 b

9 c 19 b 29 d 39 c 49 d 10 a 20 a 30 b 40 c 50 b