ESE-Electronics & Telecommunication Engineering MCQs

Q3. a valence electron jumping into an acceptor state because of a photon’s energy Which of the above statements is/are correct?

1. 1 only
2. 2 only
3. 3 only
4. 1, 2 and 3

Answer: D

Q3. Thermal runaway is not possible in FET because as the temperature of the FET increase

1. mobility decreases
2. trans-conductance increases
3. drain current increases
4. trans-conductance decreases

Answer: A

Q4. If an input impedance of op-amp is finite, then which one of the following statements related to virtual ground is correct ?

1. Virtual ground condition may exist.
2. Virtual ground condition cannot exist
3. In case of op-amp, virtual ground condition always exists.
4. Cannot make a valid declaration

Answer: B

Q5. Hysteresis is desirable in a Schmitt-trigger because

1. energy is to be stored/discharged in parasitic capacitances
2. effects of temperature variations would be compensated
3. devices in the circuit should be allowed time for saturating and de-saturation
4. it would prevent noise from causing false triggering

Answer: D

Q6. In a photoconductive cell the resistance, of the semiconductor material varies with intensity of incident light.

1. directly
2. inversely
3. exponentially
4. logarithmically

Answer: B

Q7. In graded index multimode optical fiber the refractive index of the core is

1. uniform across its radial distance except for the cladding
2. maximum at the fiber axis and decreased stepwise towards the cladding
3. maximum at the fiber axis and decreases gradually towards the cladding.
4. maximum at the fiber axis and increases stepwise towards the cladding

Answer: C

Q9. The slip of a 400 V, 3-phase, 4-pole, 50 Hz machine running at 1440 r.p.m. is

1. 6%
2. 5%
3. 4%
4. 3%

Answer: C

Q10. 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

1. 4.0 Hz
2. 3.5 Hz
3. 2.5 Hz
4. 2.0 Hz

Answer: C