BASIC ELECTRONICS
MAHESH PRASANNA K., ECE, AIET Page 1
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
c) can’t say d) none of the above
8.] The resistance of a good conductor _____________ with temperature. a) increases b) decreases
c) can’t say d) none of the above
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
c) conduction band d) forbidden band
15.] The energy band in relation to valence electrons is termed as ___________.
a) valence band b) energy band
c) conduction band d) forbidden 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
c) conduction band d) forbidden 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
c) conduction band d) forbidden 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
c) donor atoms d) acceptor atoms
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 ________________.
a) majority charge carriers b) minority charge carriers c) donor atoms d) acceptor atoms
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32.] In a p-type semiconductor material electrons are ________________.
a) majority charge carriers b) minority charge carriers c) donor atoms d) acceptor atoms
33.] The trivalent impurity atom, like gallium, added to pure germanium material
is termed as ____________. a) majority charge carriers b) minority charge carriers
c) donor atoms d) acceptor atoms
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
c) un-biased d) no-biased
43.] A p-n junction conducts when it is _________________.
a) forward biased b) reverse biased
c) un-biased d) no-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
c) can’t say d) none of the above
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
c) collector d) none of these
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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
c) collector d) none of these
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
c) collector d) none of these
28.] γ is the ratio of change in emitter current to the change in _________
current.
a) emitter b) base
c) collector d) none of these
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
c) both (a) and (b) d) neither (a) nor (b)
4.] In a _____________, the inputs and outputs can take only two values; 0 and
1.
a) digital ICs b) linear ICs
c) both (a) and (b) d) neither (a) nor (b)
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
c) very high d) very low
7.] The output impedance of an ideal Op-Amp is _____________.
a) infinity b) zero
c) very high d) very low
8.] The bandwidth of an ideal Op-Amp is _____________.
a) infinity b) zero
c) very high d) very low
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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c) very high d) very low
10.] The voltage gain of a practical Op-Amp is _____________.
a) infinity b) zero
c) very high d) very low
11.] The input impedance of a practical Op-Amp is _____________.
a) infinity b) zero
c) very high d) very low
12.] The output impedance of a practical Op-Amp is _____________.
a) infinity b) zero
c) very high d) very low
13.] When equal voltages are applied to two input terminals of a practical Op-
Amp, the output is ____________.
a) infinity b) zero
c) very high d) very low
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.