Electrical Engineering Objective Questions MCQ part -1

All Questions from ssc electrcal je exam 2008

1. A relay performs the function is

(a) Fault isolation

(b) Fault detection

(c) Fault prevention

(d) All the above

2. HRC fuse provides best protection against

(a) Open circuit

(b) Overload

(c) Reverse current

(d) Short circuit

3. The scale of moving iron (M.I.) instrument is

(a) Uniform      (b) Cramped

(c) Linear          (d) All the above

4. The power factor of industrial loads is generally

(a) Unity                (b) Lagging

(c) Leading            (d) Zero

5. The value of demand factor is

(a) Less than one   (b) Greater than one

(c) Equal to one     (d) Zero

6. The slip of an induction motor under full load

Condition is about

(a) 0.1       (b) 0.03

(c) 0.2        (d) 0.8

Slip of induction motor varies between 1% to 3% i.e. 0.01 to 0.03.

7. The motor used in ceiling fans is

(a) Resistance split phase motor

(b) Capacitor start motor

(c) Capacitor start capacitor run motor

(d) Slip ring motor

8. A Dynamometer type wattmeter responds to the

(a) Average value of active power

(b) Average value of reactive power

(c) Peak value of active power

(d) Peak value of reactive power

9. Which of the following meters is an integrating type Instrument?

(a) Ammeter     (b) voltmeter

(c) Wattmeter   (d) energy meter

10. For battery charging, which of the following DC generators is used?

(a) DC series generator

(b) DC shunt generator

(c) Short shunt compound generator

(d) Long shunt compound generator

11. The no load speed of DC series motor is

(a) Very small     (b) Medium

(c) Very high        (d) Small

12. A circuit component that opposes the change in circuit voltage is

(a) Resistance     (b) capacitance

(c) Inductance     (d) all the above

13. A series resonant circuit implies….

(a) Zero power factor and maximum current

(b) Unity power factor and maximum current

(c) Unity power factor and minimum current

(d) Zero power factor and minimum current

14. A current i = (10 + 10 sin t) amperes is passed through moving iron type ammeter. Its reading will be

15. A DC ammeter has resistance of 0.1 Ω and current Range is 0 – 100 A. If the range is to 0 – 500 A, then meter requires shunt resistance of

(a) 0.010 Ω      (b) 0.011 Ω

(c) 0.025 Ω      (d) 1.0 Ω

16. In which type of welding is a pool of molten metal

Used?

(a) Electro slag     (b) Submerged arc

(c) MIG                 (d) TIG

17. Plan and butt welds may be used on materials upto

Approximately

(a) 25 mm thick       (b) 40 mm thick

(c) 50 mm thick        (d) 70 mm thick

18. In arc welding, arc is created between the

Electrode and work by

(a) Flow of current

(b) Voltage

(c) Material thickness

(d) Contact resistance

19. Mho relay is used to protect

(a) Long transmission line

(b) Medium length line

(c) Short length line

(d) All the above

20. For arc heating, the electrodes are made of

(a) Copper                   (b) Aluminium

(c) Graphite                 (d) ACSR conductor

21. the most common type of three phase in

Unsymmetrical fault is

(a) Single line to ground

(b) Line to line

(c) Double line to ground

(d) Three phase

22. If supply frequency increases, the skin effect is

(a) Decreased            (b) Increased

(c) Remains same      (d) none of these

23. A PN junction is

(a) A rectifier         (b) an amplifier

(c) An insulator       (d) an oscillator

24. Megger is an instrument is measures

(a) A very low resistance

(b) Insulation resistance

(c) Q of coil

(d) Inductance of coil

25. Arc lamp operates at

(a) Low lagging power factor

(b) High leading power factor

(c) Unity power factor

(d) Zero power factor

26. The value of V in the circuit shown in the given Figure is

(a) 1 V                (b) 2 V

(c) 3 V                (d) 4 V

27. Two heaters rated at 1000 W, 250 V each are Connected in series across a 250 V, 50 Hz AC Mains. The total power drawn from the supply would be…..

(a) 1000 watt     (b) 500 watt

(c) 250 watt        (d) 2000 watt

Rating of heaters = (1000W, 250 V) 
R = v2/ P 
=  250*250/ 1000 = 62.5 Ω
both heater in series so eq. resistance=  62.5+62.5 = 125.0Ω
Power drawn 
P = v2/R
 =250*250/125 = 500 watt 


28. Area of hysteresis loop represents

(a) Copper loss

(b) Eddy current loss

(c) Dielectric loss

(d) Hysteresis loss

29. Two coupled coils with L1 = L2 = 0.6 H have a Coupling coefficient of K = 0.8. The turns of N1/N2 Is

(a) 4                     (b) 2

(c) 1                      (d) 0.5

we know that






=1

30. The efficiency for maximum power transfer to the Load is

(a) 25%             (b) 50%

(c) 75%             (d) 100%

31. In synchronous motor, minimum armature current Occurs at

(a) Zero power factor

(b) Leading power factor

(c) Lagging power factor

(d) Unity power factor

32. High speed alternators usually have

(a) Salient pole rotor

(b) Cylindrical rotor

(c) Both salient pole and cylindrical rotor

(d) None of the above

33. The field winding of an alternator requires

(a) DC supply

(b) AC supply

(c) Pulsating DC

(d) Any one of the above

34. The rotor input when rotor copper loss in an Induction motor is 600 W and slip is 3% is

(a) 18 kW      (b) 200 kW

(c) 20 kW       (d) 25 kW

Rotor input

35. Inter poles are meant for

(a) Increasing the speed of the motor

(b) Increasing the main field

(c) Strengthening the main field

(d) Reducing sparking at the commutator

36. The purpose of the conservator in a transformer is

(a) To cool the winding

(b) To prevent moisture in the transformer

(c) To prevent short circuit of primary and

Secondary winding

(d) To take up contraction and expansion of oil

37. In case of a power transformer, the no load current In terms of rated current is

(a) 10 to 20%               (b) 2 to 6%

(c) 15 to 30%                (d) 30 to 50%

38. If copper loss of transformer at 7/8^th full load is 4900W, then its full load copper loss would be….

(a) 5600 W    (b) 6400 W

(c) 373 W       (d) 429 W

full load copper loss= x

 x (7/8)*(7/8) = 4900

            x = 6400 watt