ESE-Electronics & Telecommunication Engineering MCQs
1. Consider the following statements:
The output of a linear circuit, driven with a sine wave at a frequency f, is itself a sine wave
1. at the same frequency
2. with chance of changed amplitude
3. with chances of changed amplitude and phase
Which of the above statements is/are correct?
(a) 1 and 2
(b) 1 only
(c) 1 and 3
(d) 2 only
Ans. (c)
2. Consider the following statements:
The main contribution to photo conduction is by
1. the generation of electron and hole pair by a photon
2. a donor electron jumping into the conduction band because of a photon’s energy
3. a valence electron jumping into an acceptor state because of a photon’s energy Which of the above statements is/are correct?
(a) 1 only
(b) 2 only
(c) 3 only
(d) 1, 2 and 3
Ans. (d)
3. Thermal runaway is not possible in FET because as the temperature of the FET increase
(a) mobility decreases
(b) trans-conductance increases
(c) drain current increases
(d) trans-conductance decreases
Ans. (a)
4. If an input impedance of op-amp is finite, then which one of the following statements related to virtual ground is correct ?
(a) Virtual ground condition may exist.
(b) Virtual ground condition cannot exist
(c) In case of op-amp, virtual ground condition always exists.
(d) Cannot make a valid declaration
Ans. (b)
5. Hysteresis is desirable in a Schmitt-trigger because
(a) energy is to be stored/discharged in parasitic capacitances
(b) effects of temperature variations would be compensated
(c) devices in the circuit should be allowed time for saturating and de-saturation
(d) it would prevent noise from causing false triggering
Ans. (d)
6. In a photoconductive cell the resistance, of the semiconductor material varies with intensity of incident light.
(a) directly
(b) inversely
(c) exponentially
(d) logarithmically
Ans. (b)
7. In graded index multimode optical fiber the refractive index of the core is
(a) uniform across its radial distance except for the cladding
(b) maximum at the fiber axis and decreased stepwise towards the cladding
(c) maximum at the fiber axis and decreases gradually towards the cladding.
(d) maximum at the fiber axis and increases stepwise towards the cladding
Ans. (c)
8. Consider the following factors:
1. Number of turns of the coil
2. Length of the coil
3. Area of cross-section of the coil
4. Permeability of the core
On which of the above factors does inductance, depend?
(a) 1, 2 and 3 only
(b) 1, 3 and 4 only
(c) 1, 2, 3 and 4
(d) 2 and 4 only
Ans. (c)
9. The slip of a 400 V, 3-phase, 4-pole, 50 Hz machine running at 1440 r.p.m. is
(a) 6%
(b) 5%
(c) 4%
(d) 3%
Ans. (c)
10. A 500 HP, 440 V, 3-phase, 50 Hz induction motor runs at 950 r.p.m. when on full load with a synchronous speed of 1000 r.p.m. for this condition, the frequency of the rotor current will be
(a) 4.0 Hz
(b) 3.5 Hz
(c) 2.5 Hz
(d) 2.0 Hz
Ans. (c)
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