basic electronics objective type questions

BASIC ELECTRONICS

MAHESH PRASANNA K., ECE, AIET

OBJECTIVE TYPE QUESTIONS

UNIT 1: SEMICONDUCTOR DIODES & APPLICATIONS

1.] Flow of electrons is generally termed as _____________.

a) electric current b) electric shock c) semiconductor d) none of the above

2.] A _______________ is a material which offers very little resistance to the flow of current through it.

a) good conductor b) insulator

c) semiconductor d) none of the above

3.] The resistance offered by ______________ is extremely large for the flow of

current through it.

a) good conductor b) insulator c) semiconductor d) none of the above

4.] The materials which behave like perfect insulators at low temperatures & at higher temperatures, they behave like a good conductors are termed as ________.

a) good conductor b) insulator

c) semiconductor d) none of the above

5.] The conductivity of a semiconductor _____________ with temperature.

a) increases b) decreases

c) can’t say d) none of the above

6.] The conductivity of a good conductor _____________ with temperature.

a) increases b) decreases c) can’t say d) none of the above

7.] The resistance of a semiconductor _____________ with temperature. a) increases b) decreases


8.] The resistance of a good conductor _____________ with temperature. a) increases b) decreases


9.] The charge of an electron is ___________________.

a) 1.602*10+27 Coulomb b) 1.602*10-27 Coulomb

c) 1.602*10+19 Coulomb d) 1.602*10-19 Coulomb

10.] The total number of electrons in an atom depends upon ____________.

a) the atomic mass b) the atomic weight

c) the atomic number d) the atomic size

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11.] In any atom, the number of electrons in the last orbit (i.e., the outermost orbit or the valence orbit) is limited to ________________.

a) 4 b) 8

c) 10 d) 12

12.] In any atom, the outermost orbit is called ______________.

a) valence orbit b) energy band

c) conduction band d) forbidden band

13.] The electrons present in the valence orbit are termed as _______________.

a) valence electrons b) free electrons c) can’t say d) none of the above

14.] The range of energies possessed by the electrons of any one orbit of all

atoms is referred as _____________________. a) valence band b) energy band


15.] The energy band in relation to valence electrons is termed as ___________.

a) valence band b) energy band


16.] Electrons which are removed from the valence orbits of atoms, which are

freely available for conduction, are termed as __________________.

a) valence electrons b) free electrons c) can’t say d) none of the above

17.] The range of energies possessed by the free electrons is termed as ______. a) valence band b) energy band


18.] The void (or gap) separating conduction band and valence band, and no

electron can exist in this void is termed as ______________.

a) valence band b) energy band


19.] In a metal, the number of valence electrons is ___________.

a) less than 4 b) equal to 4 c) greater than 4 d) equal to 8

20.] In a semiconductor material, the number of valence electrons is

___________. a) less than 4 b) equal to 4

c) greater than 4 d) equal to 8

21.] In an insulator , the number of valence electrons is ___________.

a) less than 4 b) equal to 4

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c) greater than 4 d) equal to 8

22.] The current which results in a semiconductor material due to the movement

of holes is termed as ___________________.

a) hole current b) electron current

c) negative current d) none of the above

23.] A semiconductor in its pure form is termed as __________________.

a) intrinsic semiconductor b) extrinsic semiconductor c) p-type semiconductor d) n-type semiconductor

24.] The process of adding impurity to a pure semiconductor material, in order to increase its conductivity is called as __________________.

a) dancing b) doping

c) creating holes d) creating electrons

25.] A semiconductor to which an impurity is added with view to increase its

conductivity is termed as __________________.

a) intrinsic semiconductor b) extrinsic semiconductor c) p-type semiconductor d) n-type semiconductor

26.] If a pentavalent impurity like arsenic or antimony or phosphorus is added to pure germanium or silicon, a _____________________ results.

a) intrinsic semiconductor b) extrinsic semiconductor

c) p-type semiconductor d) n-type semiconductor

27.] In a n-type semiconductor material electrons are ________________.

a) majority charge carriers b) minority charge carriers

c) donor atoms d) acceptor atoms

28.] In a n-type semiconductor material holes are ________________.

a) majority charge carriers b) minority charge carriers c) donor atoms d) acceptor atoms

29.] The pentavalent impurity atom, like arsenic, added to pure germanium

material is termed as ____________. a) majority charge carriers b) minority charge carriers


30.] If a trivalent impurity like gallium or indium or aluminium is added to pure

germanium or silicon, a _____________________ results.

a) intrinsic semiconductor b) extrinsic semiconductor

c) p-type semiconductor d) n-type semiconductor

31.] In a p-type semiconductor material holes are ________________.


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32.] In a p-type semiconductor material electrons are ________________.


33.] The trivalent impurity atom, like gallium, added to pure germanium material

is termed as ____________. a) majority charge carriers b) minority charge carriers


34.] In extrinsic semiconductors, conduction of current is due to ____________.

a) electrons only b) holes only

c) both electrons and holes d) neither electrons nor holes

35.] Doping an intrinsic semiconductor with pentavalent impurity atom

__________________.

a) raises the Fermi level b) lowers the Fermi level c) do not affect the Fermi level d) none of the above

36.] Doping an intrinsic semiconductor with trivalent impurity atom __________. a) raises the Fermi level b) lowers the Fermi level

c) do not affect the Fermi level d) none of the above

37.] In a pure semiconductor, the Fermi level lies _____________ of the

forbidden energy gap.

a) exactly in the middle b) at the lower part

c) at the upper part d) none of the above

38.] In a p-n junction, the potential built across the junction, after diffusion has

stopped, is termed as _______________. a) barrier potential b) developed potential

c) p-n potential d) none of the above

39.] The barrier potential is about ______________ of germanium.

a) 0.1V b) 0.3V

c) 0.7V d) 1.5V

40.] The barrier potential is about ______________ of silicon.

a) 0.1V b) 0.3V

c) 0.7V d) 1.5V

41.] If an external voltage is applied across the p-n junction such that it

neutralizes the barrier potential and causes conduction through the junction, the p-

n junction is said to be ______________. a) forward biased b) reverse biased

c) un-biased d) no-biased

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42.] If an external voltage is applied across the p-n junction such that the

depletion layer widens and the barrier potential increases, the p-n junction is said to be ______________.

a) forward biased b) reverse biased


43.] A p-n junction conducts when it is _________________.

a) forward biased b) reverse biased


44.] A p-n junction blocks conduction when it is ________________.

a) forward biased b) reverse biased c) un-biased d) no-biased

45.] The direction of conventional current is always ____________ to the

direction of drifting electrons. a) same b) opposite


46.] The slope of DC load line is _______________.

a) – 1/IL b) – 1/VL

c) – 1/RL d) – 1/If

47.] The Iav for a half-wave rectifier is _____________.

a) Im/ b) Im/2

c) 2Im/ d) Im/2

48.] The IRMS for a half-wave rectifier is ______________.

a) Im/ b) Im/2

c) 2Im/ d) Im/2

49.] The Iav for a full-wave rectifier is _____________. a) Im/ b) Im/2

c) 2Im/ d) Im/2

50.] The IRMS for a full-wave rectifier is _____________.

a) Im/ b) Im/2

c) 2Im/ d) Im/2

51.] The efficiency of a half-wave rectifier is _____________. a) 40.6% b) 81.2%

c) 0.483% d) 1.21%

52.] The efficiency of a full-wave rectifier is _____________. a) 40.6% b) 81.2%

c) 0.483% d) 1.21%

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53.] The ripple factor of a half-wave rectifier is _____________.

a) 40.6 b) 81.2 c) 0.483 d) 1.21

54.] The ripple factor of a full-wave rectifier is _____________.

a) 40.6 b) 81.2 c) 0.483 d) 1.21

55.] An inductor ___________ to pass through it.

a) allows DC b) blocks DC

c) allows AC d) blocks AC

56.] A capacitor ___________ to pass through it.

a) allows DC b) blocks DC

c) allows AC d) blocks AC

57.] The switch off time of diodes is longer due to _______________.

a) the diffusion capacitance b) the forward bias c) the reverse bias d) none of the above

UNIT 2 & 3: TRANSISTORS & BIASING METHODS

1.] The direction of arrow head placed on the emitter of a transistor represents

________________.

a) the direction of motion of holes b) the direction of motion of electrons c) both (a) and (b) d) none of the above

2.] The direction of flow of electrons is ____________ to the direction of motion of holes.

a) same as b) opposite

c) parallel d) perpendicular

3.] During normal working of transistor as amplifier, the emitter diode is

______________.

a) unbiased b) forward biased c) reverse biased d) none of the above

4.] During normal working of transistor as amplifier, the collector diode is ______________.

a) unbiased b) forward biased

c) reverse biased d) none of the above

5.] The reverse current which results in a transistor due to minority charge

carriers across the collector-to-base junction is called as ________________.

a) base current b) emitter current

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c) collector current d) collector-to-base leakage current

6.] A transistor can be visualized as a ___________ port network.

a) one b) two

c) three d) four

7.] Varying the input current by varying the input voltage at constant output

voltage is _____________________.

a) static input characteristics b) static output characteristics c) transistor i/o characteristics d) none of the above

8.] Varying the output current by varying the output voltage at constant input current is _____________________.

a) static input characteristics b) static output characteristics

c) transistor i/o characteristics d) none of the above

9.] The ratio of change in collector current to the change in emitter current at

constant collector to base voltage is ___________. a) α b) β

c) γ d) π

10.] The ratio of change in collector current to the change in base current at

constant collector to emitter voltage is ___________. a) α b) β

c) γ d) π

11.] The ratio of change in emitter current to the change in base is ___________. a) α b) β

c) γ d) π

12.] A ______________ circuit has a very high input resistance and very low

output resistance. a) common base b) common emitter

c) common collector d) none of the above

13.] In the saturation region, the emitter-base & collector-base junctions are

_________________ biased.

a) forward b) reverse c) unbiased d) none of these

14.] In the cut-off region, the emitter-base & collector-base junctions are

_________________ biased. a) forward b) reverse

c) unbiased d) none of these

15.] The intersection of DC load line and the output characteristics of a transistor

is called _____________________.

a) Q – Point b) quiescent Point

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c) operating Point d) all of these

16.] The biasing circuit which gives most stable operating point is _________.

a) base bias b) collector-to-base bias

c) voltage-divider bias d) none of these

17.] The collector-to-base bias circuit is also known as _______________.

a) base bias b) voltage-divider bias

c) voltage feedback bias circuit d) none of these

18.] The reverse saturation current doubles for every _________ 0C rise in

temperature. a) 40 b) 30

c) 20 d) 10

19.] The reverse saturation current __________ for every 100C rise in temperature.

a) doubles b) triples

c) quadruples d) none of these

20.] ICBO doubles for every _________ 0C rise in temperature.

a) 40 b) 30 c) 20 d) 10

21.] ICBO __________ for every 100C rise in temperature.

a) doubles b) triples c) quadruples d) none of these

22.] The stability factor ‘S’ is the rate change of _____________ current with respect to reverse saturation current.

a) emitter b) base

c) collector d) none of these

23.] α is the ratio of change in __________ current to the change in emitter

current at constant collector to base voltage.

a) emitter b) base

c) collector d) none of these 24.] β is the ratio of change in __________ current to the change in base current

at constant collector to emitter voltage.

a) emitter b) base c) collector d) none of these

25.] γ is the ratio of change in __________ current to the change in base current.

a) emitter b) base


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26.] α is the ratio of change in collector current to the change in _________

current at constant collector to base voltage. a) emitter b) base


27.] β is the ratio of change in collector current to the change in _________

current at constant collector to emitter voltage. a) emitter b) base


28.] γ is the ratio of change in emitter current to the change in _________

current.

a) emitter b) base


29.] The emitter area in a transistor is considerably __________ than the

collector area.

a) smaller b) greater c) smaller or greater d) none of these

30.] The collector area is slightly _________ doped than the emitter. a) more b) less

c) more or less d) none of these

31.] The depletion layer width at the collector junction is _________ than the

depletion layer width at the emitter junction.

a) more b) less

c) more or less d) none of these

32.] In a transistor, the emitter area is _________ doped.

a) heavily b) lightly c) moderately d) none of these

33.] In a transistor, the base region is _________ doped. a) heavily b) lightly

c) moderately d) none of these

34.] In a transistor, the collector area is _________ doped. a) heavily b) lightly

c) moderately d) none of these

35.] In a transistor, the depletion layer penetrates deeply into the __________

region.

a) base b) emitter c) collector d) none of these

36.] In a ______________, the current is mainly due to electrons.

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a) PNP transistor b) NPN transistor

c) BJT transistor d) UJT transistor

37.] In a ______________, the current is mainly due to holes.

a) PNP transistor b) NPN transistor

c) BJT transistor d) UJT transistor

38.] In CB configuration, when reverse bias voltage VCB increases, the width of

the depletion region also increases, which reduces the electrical base width. This effect is called as _________________.

a) early effect b) base width modulation

c) (a) or (b) d) none of these

39.] In CB configuration, when reverse bias voltage VCB increases above the

VCB max, increase in depletion region is such that it penetrates into base until it

makes contact with emitter-base depletion region. This condition is called _______. a) punch-through effect b) reach-through effect

c) (a) or (b) d) none of these

40.] The collector-to-base bias provides __________ stability than the base bias

circuit.

a) more b) less c) more or less d) none of these

41.] The voltage divider bias provides the _______ stability against hFE variations.

a) least b) greatest c) more or less d) none of these

UNIT 5: AMPLIFIERS & OSCILLATORS

1.] Audio amplifiers can amplify signals of frequencies which lie in the range of

_____________.

a) 20Hz to 20KHz b) 20Hz to 20MHz c) 20Hz to 200KHz d) 20Hz to 200MHz

2.] In a _________ amplifier, the collector current flows throughout the input signal cycle.

a) class A b) class B

c) class C d) class AB

3.] In a __________ amplifier, the collector current flows only during the

positive half cycles of the input signal.

a) class A b) class B c) class C d) class AB

4.] In a ____________ amplifier, the collector current flows for less than half of the period of the input signal.

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a) class A b) class B

c) class C d) class AB

5.] In a ____________ amplifier, the collector current flows for more than half

of the input signal period, but not throughout the full cycle.

a) class A b) class B c) class C d) class AB

6.] The coupling capacitor, CC, in a R-C coupled amplifier is used to _________. a) bypass the output to ground b) couple the output to next stage

c) bypass the emitter current d) couple the emitter current to next stage

7.] The range of frequencies in which the amplifier gain is either equal to greater

than 70.7% of the maximum gain is called as _______________.

a) channel-width b) frequency-width

c) band-width d) none of these

8.] The range of frequencies at the limits of which, the voltage gain falls by 3dB

is called as _______________. a) channel-width b) frequency-width

c) band-width d) none of these

9.] In a common-emitter amplifier, there is a phase shift of _________ between

input and output voltages.

a) 900 b) 1800

c) 3600 d) 00

10.] When the phase of the feedback signal is same as that of the input, then it is

called ______________. a) positive feedback b) negative feedback

c) no feedback d) none of these

11.] When the phase of the feedback signal is out of phase with that of the input,

then it is called ______________.

a) positive feedback b) negative feedback

c) no feedback d) none of these

12.] Tank circuit comprises of _____________.

a) an inductor in parallel with a capacitor b) an inductor in series with a capacitor

c) an inductor in parallel with a resistor d) an inductor in series with a resistor

13.] R-C oscillators are usually used in ___________ range. a) audio frequency b) radio frequency

c) video frequency d) ultra high frequency

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UNIT 6: OPERATIONAL AMPLIFIERS

1.] The characteristics of ______________ changes with application of external voltage.

a) an active element b) a passive element

c) both (a) and (b) d) neither (a) nor (b)

2.] The characteristics of ______________ will not change on application of

external voltage.

a) an active element b) a passive element c) both (a) and (b) d) neither (a) nor (b)

3.] In _____________, the outputs are proportional to inputs.

a) digital ICs b) linear ICs


4.] In a _____________, the inputs and outputs can take only two values; 0 and

1.

a) digital ICs b) linear ICs


5.] The voltage gain of an ideal Op-Amp is _____________.

a) infinity b) zero

c) very high d) very low

6.] The input impedance of an ideal Op-Amp is _____________.

a) infinity b) zero


7.] The output impedance of an ideal Op-Amp is _____________.

a) infinity b) zero


8.] The bandwidth of an ideal Op-Amp is _____________.

a) infinity b) zero


9.] When equal voltages are applied to two input terminals of an ideal Op-Amp,

the output is ____________.

a) infinity b) zero

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10.] The voltage gain of a practical Op-Amp is _____________.

a) infinity b) zero


11.] The input impedance of a practical Op-Amp is _____________.

a) infinity b) zero


12.] The output impedance of a practical Op-Amp is _____________.

a) infinity b) zero


13.] When equal voltages are applied to two input terminals of a practical Op-

Amp, the output is ____________.

a) infinity b) zero


14.] The ratio of the differential gain of an Op-Amp to its common mode gain is

______________.

a) PSRR b) input off-set current

c) output off-set current d) CMRR

15.] In a practical Op-Amp, there will be a small output voltage even when the

inputs are zero. This is called _____________.

a) output off-set current b) output off-set voltage

c) input off-set current d) input off-set voltage

16.] The DC voltage which makes the output off-set voltage zero, when the other

terminal is zero is called _____________.

a) output off-set current b) output off-set voltage

c) input off-set current d) input off-set voltage

17.] The maximum rate at which the Op-Amp output can change is ___________.

a) run rate b) ratio rate

c) slew rate d) none of these

18.] Slew rate is expressed in terms of ______________.

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a) volts/µs b) volts-µs

c) µs/volts d) µs-volts

19.] The time period for which the trace remains on a fluorescent screen after the

applied signal becomes zero is known as ____________.

a) existence b) shadow

c) persistence d) trace

20.] The time-base generator in a CRO is used to generate _______________.

a) the saw-tooth voltage b) the square wave

c) the DC voltage d) the AC voltage

21.] When the input is applied to the inverting input terminal of an Op-Amp, then

the output is ______________ with the input.

a) 900 out of phase b) 1800 out of phase

c) 3600 out of phase d) in phase

22.] When the input is applied to the non-inverting input terminal of an Op-Amp,

then the output is ______________ with the input.

a) 900 out of phase b) 1800 out of phase

c) 3600 out of phase d) in phase

UNIT 7: COMMUNICATION SYSTEMS & NUMBER SYSTEMS

1.] If the amplitude of the carrier wave is altered in accordance with the strength

of the modulating signal, then it is _________________. a) amplitude modulation b) frequency modulation

c) amplitude communication d) frequency communication

2.] If the frequency of the carrier wave is altered in accordance with the strength of the modulating signal, then it is _________________.

a) amplitude modulation b) frequency modulation

c) amplitude communication d) frequency communication

3.] The process of getting back the modulating signal from the modulated wave

is _________________.

a) modulation b) re-modulation c) demodulation d) none of these

4.] The modulation index ‘m’ for amplitude modulation is _____________. a) Vc/Vm b) Vc * Vm

c) Vm + Vc d) Vm/Vc

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5.] The modulation index ‘mf’ for frequency modulation is _____________.

a) f/fm b) f * fm

c) f - fm d) fm/f

6.] Usually, the intermediate frequency is _______________.

a) 455 MHz b) 455 KHz

c) 455 Hz d) 455 GHz

9.] The decimal equivalent of binary number 1110 is ________________.

a) 15 b) 16

c) 18 d) 14

10.] 110112 = X10, then

a) X = 27 b) X = 37

c) X = 17 d) X = 12

11.] The 1’s compliment of 1110 is __________.

a) 1111 b) 0001

c) 0010 c) 0000

12.] The 2’s compliment of 1110 is ____________.

a) 1111 b) 0001

c) 0010 d) 0000

13.] If 4710 = X8, then

a) X = 37 b) X = 27

c) X = 74 d) X = 57

14.] The octal equivalent of 001001011011(2) is _________________.

a) 3311(8) b) 3113(8)

c) 1133(8) d) 1331(8)

15.] If 110211102 = X16, then

a) X = AB b) X = CD

c) X = EF d) X = DE

16.] If 5810 = XBCD, then

a) X = 01011000 b) X = 01010001

c) X = 10101000 c) 10100001

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UNIT 8: DIGITAL ELECTRONICS

1.] The OR operation implies ______________.

a) boolean addition b) boolean multiplication

c) Boolean subtraction d) boolean division

2.] The AND operation implies ______________.

a) boolean addition b) boolean multiplication

c) Boolean subtraction d) boolean division

3.] The output of a NAND gate is ___________, when all the inputs are high.

a) low b) high

c) low or high d) none of these

4.] The output of a NOR gate is ___________, when all the inputs are low.

a) low b) high

c) low or high d) none of these

5.] A bubbled AND gate and a _____________ are equivalent.

a) XOR gate b) XNOR gate

c) NOR gate d) NAND gate

6.] A bubbled OR gate and a _____________ are equivalent.

a) XOR gate b) XNOR gate

c) NOR gate d) NAND gate

____________***____________

By – MAHESH PRASANNA K.,

Dept. of E & C, AIET.

basic electronics objective type questions

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