Electronics mcqs

Mcqs Electronics Engineering

Mcqs Electronics Engineering

1. When four resistances of 2W 1W; 5W 2W; 10W 5W and 15W 10 W are connected in parallel, the greatest power is absorbed by

  • 2 W, 1 W
  • 5 W, 2 W
  • 10 W, 5W
  • 15 W, 10 W

2. A moving coil instrument has a resistance of 10 W and gives full scale deflection when carrying a current of 50 mA.  To measure current upto 100 A, we will have to connect

  • 10 W resistance in series
  • 10 W resistance in parallel
  • 10/1999 W resistance in series
  • 10/1999 W resistance in parallel

3. The ripple voltage in the output of a single phase half wave rectifier with 10 V rectified dc voltage with resistive load and without filter will be

  • 12.1 volt
  • 1.21 volt
  • 0.482 volt
  • 4.82 volt

4. The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is

  • Star/Star
  • Delta/Delta
  • Delta/Star
  • Star/Delta

5. Transformer oil tester is used to know

  • Permittivity
  • Permeability
  • Dielectric strength
  • Resistance of the oil

6. Plate separation of a parallel plate air capacitor is reduced keeping the voltage constant.  The energy stored in the capacitor shall

  • Increase
  • Decrease
  • Remain constant
  • Remain zero

7. 1 Ampere of current is defined as

  • 1 volt/sec
  • 1 coulomb/sec
  • 1 ohm/second
  • 1 coulomb

8. The synchronous motor can be used as a capacitor

  • By increasing excitation
  • By decreasing excitation
  • By increasing speed
  • By decreasing speed

9. The actual speed of an induction motor is always

  • Less than synchronous speed
  • More than synchronous speed
  • Equal to synchronous speed
  • None of the above.

10. The purpose of connecting a capacitor in flourescent tube circuit is

  • To increase switching on time
  • To decrease switching off time
  • To increase power factor
  • To decrease power consumption

11. The condition for parallel operation of two inverters is

  • Amplitude of voltages should be same.
  • Frequency of voltages should be same.
  • Both the voltages should be in same phase.
  • All the three above.

12. A 60 Hz, 2 pole alternator should run at

  • a. 3000 r.p.m.                  c.         1500 r.p.m.
  • b. 3600 r.p.m.                  d.         1800 r.p.m.

13. The purpose of a governer in a DG set is

  • To regulate the speed.
  • To regulate the voltage
  • To regulate the power
  • To regulate the current.

14.       A   S C R can conduct

  • In one direction only.
  • In both directions.
  • Only when gate is triggered.
  • None of the above.

15. The cut-in voltage of a silicon diode is approx.

  • 0.7 volt
  • 0.3 volt
  • 1.4 volt
  • None of the above.

16. The step Recovery Diode is used as

  • Frequency adder
  • Frequency subtractor
  • Frequency multiplier
  • None of the above.

17. The isolation between input and output in case of opto coupler is of the order of

  • 10 Ohms
  • 1010 ohms
  • 103 ohms
  • None of the above.

18. The transistor configuration to connect 4 W speaker with 600 W output impedance audio amplifier is

  • Common Emitter
  • Common Base
  • Common Collector
  • None of the above.

19. Beta cut-off frequency of a transistor is the frequency at which the Beta is

  • 0.707 of low frequency value
  • Zero
  • Equal to low frequency value
  • None of the above.

20. Which of the following amplifier has the least distortion.

  • Class E
  • Class D
  • Class C
  • Class A

21. Pinch off voltage of a J FET is the drain to source voltage above which drain current.

  • Increases
  • Decreases
  • Remains constant
  • Becomes zero

22. Decimal equivalent of binary 1111 1111 1111 1111 is

  • 16,384
  • 65,536
  • 1000000
  • None of the above.

23. A l/2 dipole aerial is used for

  • MW
  • SW
  • Microwave
  • None of the above.

24. TCXO is preferred over LC oscillator because

  • TCXO is more stable.
  • TCXO gives more power
  • TCXO is linear.
  • None of the above.

25. The angular velocity of geo-stationary satellite is

  • Equal to the angular velocity of earth.
  • Less than the angular velocity of earth.
  • More than the angular velocity of earth
  • None of the above.

26. The battery operated pre-amplifier with a consumption of 10 Watts can work on battery of 12 volt, 100 AH having efficiency of 50% for

  • 120 hrs.
  • 60 hrs.
  • 100 hrs.
  • 10 hrs.

27. Low pass filter with cut off frequency of 100 kHz and high pass filter with cut off frequency of 50 kHz are connected in tandem, the resultant filter is

  • Low pass filter with cut off frequency of 100 kHz
  • High pass filter with cut off frequency of 50 kHz
  • Band pass filter with pass band from 50 kHz to 100 kHz.
  • None of the above.

28. In case of oil fire, the fire extinguisher used is

  • Soda Acid
  • Foam
  • Carbon dioxide
  • Carbon Tetra chloride

29.The output of a 2-input NAND gate with high at both the inputs will be

  • High
  • Low
  • High & low
  • None of the above.

30. The input impedance of an op-amp is

  • High
  • Low
  • Medium
  • None of the above

Answers

1(a), 2 (d), 3 (a), 4 (c), 5 (c) 6 (a) 7 (b) 8 (a) 9 (a) 10 (c) 11 (d) 12 (c) 13 (a) 14 (a) 15 (a)

16 (c) 17 (b) 18 (c) 19 (a) 20 (d) 21 (c) 22 (b) 23 (b) 24 (a) 25 (a) 26 (b) 27 (c) 28 (b) 29 (b) 30 (a).