SSC JE Electrical MCQ Questions

1. The value of voltage across the diode in figure given below is

(a) Zero volt
(b) 4 V
(c) 8 V
(d) Depends upon the value of R

2. The temperature co-efficient of an intrinsic semiconductor is

(a) Zero
(b) Positive
(c) Negative
(d) Like that of metals

3. A 4-pole, 1200 rpm DC lap wound generator has 1520 conductors. If the flux per pole is 0.01 weber, the emf of generator is

(a) 608 volts
(b) 304 volts
(c) 152 volts
(d) 76 volts

4. In a 3-phase induction motor starting torque will be maximum when

(a) R₂ = 1/X₂
(b) R₂ = X₂
(c) R₂ = X₂²
(d) R₂ = √X₂

5. The ratio of resistance of a 100 ohm, 220 V lamp to that of a 100 ohm, 110 V lamp will be at respective voltages

(a) 4
(b) 2
(c) 1/2
(d) 1/4

6. Two sinusoidal equations are given as e₁ = Asin(wt + π/4) and e₂ = Bsin(wt + π/6). The phase difference between the two quantities is:

(a) 75°
(b) 60°
(c) 105°
(d) 15°

7. The moderator used in fast breeder reactor is

(a) Heavy water
(b) Graphite
(c) Ordinary water
(d) Any of the above

8. The ratio of the puncture voltage to the flashover voltage of an insulator is

(a) equal to one
(b) lower than one
(c) zero
(d) greater than one

9. Bucholtz relay cannot be used on

(a) 500 kV transformer
(b) 1000 kV transformer
(c) Three phase transformer
(d) Air cooled transformer

10. An ammeter is obtained by shunting a 30 ohm galvanometer with 30 ohm resistance. What additional shunt should be connected across it to double the range ?

(a) 15 ohm
(b) 10 ohm
(c) 5 ohm
(d) 30 ohm

11. Swamping resistances is used to compensate error due to

(a) Stray magnetic field
(b) Large supply voltage
(c) Large supply frequensy
(d) Temperature variations

12. Which of the following is of high importance in case of induction heating?

(a) voltage
(b) frequency
(c) current
(d) all the above

13. If four 10 µF capacitors are connected in parallel, the net capacitance is

(a) 2.5 µF
(b) 40 µF
(c) 20 µF
(d) 15 µF

14. Variation in dc excitation of a synchronous motor causes variation in

(a) speed of motor
(b) power factor
(c) armature current
(d) both (B) and (C)

15. The earth’s potential is taken as

(a) Infinite
(b) Supply voltage
(c) 1 volt
(d) Zero

16. The value of diversity factor is

(a) less than one
(b) greater than one
(c) equal to one
(d) any one of the above

17. The resistance welding process requires a

(a) high value of ac current at low voltage
(b) low value of ac current at high voltage
(c) high value of dc current at low voltage
(d) low value of dc current at high voltage

18. The tariff most suitable for large industrial consumers is

(a) Flat demand rate
(b) Block meter rate
(c) Two part tarrif
(d) All the above

19. Advarntage of transmitting power at high voltage is

(a) magnitude of current will be small
(b) power loss will be less
(c) it will reduce the voltage drop in the line impedance
(d) all the above

20. A FET is essentially a

(a) Current driven device
(b) Voltage driven device
(c) Power driven source
(d) Solar device

21. Differential relays are used to protect the equipment against

(a) internal faults
(b) reverse current
(c) overvoltage
(d) overcurrent

22. Skin effect exists only in

(a) Low voltage dc overhead transmission
(b) High voltage dc overhead transmission
(c) Cable carrying dc current
(d) AC transmission

23. For a 3-phase, 4-pole, 50 Hz synchronous motor the frequency, no. of poles, and the load torque are all halved. The motor speed will be

(a) 375 rpm
(b) 75 rpm
(c) 1500 rpm
(d) 3000 rpm

25. A transformer is working at its full load and its efficiency is also maximum. The iron loss is 1000 watts. Then, its copper loss at half of full load will be

(a) 250 watt
(b) 300 watt
(c) 400 watt
(d) 500 watt

Answer: (a) 250 watt