2018 FEBRUARY ELECTRICIAN THEORY SEMESTER-4

2018 FEBRUARY ELECTRICIAN THEORY SEMESTER-4

1. If a slot consists of one coil

side then the winding is called-
a) Double layer winding

b) Full pitch winding

c) Single layer winding

d) Short pitch winding

Answer:- b) Full pitch winding

2. A capacitor start, capacitor run

single phase induction motor is

basically a

a) AC series motor

b) DC series motor

c) 2 phase induction motor

d) 3 phase induction motor

Answer:- c) 2 phase induction

                     motor

3. The starting torque of a capacitor

start motor is -
a) Zero

b)Low

c) Same as rated torque

d) More than rated torque

Answer:- b)Low

4. The starling capacitor of a single phase motor is - .
a) Electrolytic capacitor

b) Ceramic capacitor

c) Paper capacitor

d) None of the above.

Answer:- a) Electrolytic capacitor

5. The motor used in household

refrigerators is -
a) DG series motor

b) DC shunt motor

c) Universal motor

d) Single phase induction

     motor.

Answer:- d) Single phase

                     induction motor

6. A capacitor start single phase

induction motor will usually

have a power factor of
a) Unity

b) 0.8 leading

c)0.6 leading

d) 0.6 lagging

Answer:- d) 0.6 lagging

7. The short coming of repulsion

motor is -
a) Variation of speed with load

b) Low power factor

c) Tendency to spark at brushes

d) All of these

Answer:- d) All of these

8. A ceiling fan of 1400 mm sweep

will have motor rating of
a) 10 to 15 waits

b) 50 to 70 watts

c) 120 to 180 watts 

b) 250 to 500 watts.

Answer:- c) 120 to 180 watts 

9. Which of the following

applications would need the

smallest size of motor?
a) Domestic motor

b) Electric clock

c) Table fan

d) Sewing machine

Answer:- b) Electric clock

10. Which of the following is

not a bio-mass source?

a) Gobar gas

b) Coal

c) Wood

d) Nuclear energy

Answer:- d) Nuclear energy

11. The source of energy of

the sun is__

a) Nuclear fission

b) Chemical reaction

c). Nuclear fusion

d) Photoelectric effect

Answer:-c). Nuclear fusion

12. Which motor would you

select for vacuum cleaners?
a) Universal motor .

b) Repulsion motor

c) Hysteresis motor

d) Reluctance motor.

Answer:- a) Universal motor

13. The advantage of*salient

poles in an alternator is -

a) Reduce noise

b) Reduced windage loss

c) Adoptability to low and

    medium speed operation

d) Reduce bearing loads

    and noise.

Answer:- c) Adoptability to low

and medium speed operation

14. Major share of power

generated in India is through

which means-
a) Hydroelectric power plants

b) Nuclear power plants

c) Thermal power plants

d) Gas turbine power plants

Answer:- ) Thermal power plants

15. A three phase alternator has

a phase sequence of RYB for is

three output voltages for
clockwise rotation. Now if the

alternator is rotated anticlockwise,

the phase sequence will be

a) RYB

b) RBY

c) BYR

d) None of these

Answer:- b) RBY

16. In an alternator, voltage

drops occurs in -

a) Armature resistance only

b) Armature resistance and

      leakage reactance

c) Armature resistance, leakage

 reactance and armature reaction

d) Armature resistance, leakage

reactance, armature reaction and earth

Answer:- c) Armature resistance,

 leakage reactance and armature

 reaction

17. The power Factor of an alternator

depends on -

a) Load

 b) Speed of rotor

c) Core losses

d) Armature losses

Answer:- a) Load

18.  The frequency of voltage

generated by. an alternator having

8 poles and rotating at 250 rpm is

a) 60 Hz

b)50Hz
c)25Hz

d) 16 2/3 Hz

Answer:- d) 16 2/3 Hz

19. A winding is having number of

slots is greater than number of polos,

 then this winding is
called-

a) Concentrated winding

b) Distributed winding

c) Full pitch winding

d) Integrated slot winding

Answer:- b) Distributed winding

20. Synchronous motor can

operate at -

a) Lagging power factor only

b) Leading power factor only

c) Unity power factor only

d) Lagging, leading and unity

   power factor only

Answer:- d) Lagging, leading

and unity power factor only

21. The damping winding in a

synchronous motor is generally used

a) To provide starting torque only

b) To reduce noise level

c) To reduce eddy currents

d) To prevent hunting and provide

the starting torque

Answer:- d) To prevent hunting and

provide the starting torque

22. The back emf set up in ihe stator

of a synchronous motor will depend on

a) Rotor speed only

b) Rotor excitation only

c) Rotor excitation and rotor speed       

d) Coupling angle, rotor speed and

Answer:- b) Rotor excitation only

23. In a synchronous motor, damper

winding is provided to -

a) Stabilize rotor motion

b) Suppress rotor oscillations

c) Develop necessary starting torque    

d) Both (a) & (c)

Answer:- d) Both (a) & (c)

24. Advantage of 'hydro-electric power

station is -

a) Low operating cost

b) Free from pollution problems

c) No fuel transportation problems       

d) All of these

Answer:- d) All of these

25. An Auto-transformer (which has

only one winding) may be used as a
a) Step-Up Transformer

b) Step-Down Transformer

c) Both (a) & (b)

d) None of the above

Answer:- c) Both (a) & (b)

26. In an Auto Transformer, The

Primary and Secondary arc ............

Coupled,
a) Only Magnetically

b) Only Electrically

c) Magnetically as well as Electrical

d)None of these

Answer:- c) Magnetically as well as

                   Electrical

27. The nominal ratio for a current

 transformer is given by -

a) (Rated primary winding current)/

(Rated secondary winding current)

b) (Number of turns in the primary

winding) / (Number of turns in the

secondary winding)

c) (Number of turns in the secondary

winding)/ (Number of turns in the

primary winding)

d) (Rated secondary winding current) /

(Rated primary winding current)

Answer:- a) (Rated primary winding

current)/ (Rated secondary winding

current)

28. The transformer ratio of the

transformer depends upon the

a) Exciting current

b) Secondary current

c) Power factor of secondary circuit

d) All of these

Answer:- d) All of these

29. Radiant efficiency of the

 luminous source depends on -
a) Shape of the source

b) Temperature of the source

c) Wavelength of light rays

d) All of these

Answer:- b) Temperature of

                     the source

30. Light waves Iravci with a

velocity of-

a)3x l0¹ºcm/s

b) 3 x 10¹²cm/s

c)3xcm/s

d)3x cm/s.

Answer:- a)3x l0¹ºcm/s

31. Carbon arc lamps commonly

used in .....

a) Domestic lighting
b) Street lighting

c) Cinema projectors

d) Photography

Answer:- c) Cinema projectors

32. The unit of solid angle is .....

a) Solid angle
b) Radian

c) Steradian

 d) Candcla

Answer:- c) Steradian

33. Candela is the unit of-
a) Luminous flux
b) Luminous intensity

c) Wavelength

d) None of these

Answer:- b) Luminous intensity

34. The unit of luminous flux is ......
a) Sleradian
b) Candela

c) Lumen

d) Lux

Answer:- c) Lumen

35. Luminous efficiency of a

fluorescent, tube is

a) 5- 10 lumens/watt

b) 15-20 lumens/watt

c) 30 - 40 lumens/watt

d) 60 - 65 lumens/watt

Answer:- d) 60 - 65 lumens/watt

36. One lumen per square meter is

the same as
a) One lux

b) One candela

c) One foot candle

d) One lumen meter

Answer:- a) One lux

37. The frequency of dickers in a

fluorescent lamp at 220 V, 50 Hz

supply will be
a) 25 per second

b) 50 per second

c) 100 per second

d) 220 per second

Answer:- c) 100 per second

38. One that is based on forward

biased PN junction is

a) Photo diode

 b) LED

c) Photo voltaic cell

d) Both (a)

Answer:- b) LED

39. Photo diode is used for

detection of

a) Visible light

b) Invisible light

c) No light

d)Both(a)&(b)

Answer:- d)Both(a)&(b)

40. Color of light emitted by

LED depends on

a) Its forward bias .

b) Its reverse bias

c) Forward current

d) Semiconductor material

Answer:- d) Semiconductor

material

41. The earth wire should not

be thinner than a

a) 20 SWG wire

b) 16 SWG wire

c) 10 SWG wire

d) 8 SWG wire

Answer:- d) 8 SWG wire

42. In automobiles the sound

is produced by horn due to

a) Magnetostriction

b) Vibrating diaphragm

c) Moving coil     

d) Oscillating coil

Answer:- b) Vibrating

                    diaphragm

43. In a constant power type

       load

a) Torque is proportional to

    speed

b) Torque is proportional to

    square of speed

c) Torque is inversely proportional

    to speed      

d) Torque is independent of speed.

Answer:- c) Torque is inversely

                   proportional to speed     

44. The frame of an induction motor

 is usually made of-
a) Silicon steel

b) Cast iron

c) Aluminium

d) Copper

Answer:- b) Cast iron

45. Slip rings arc usually made of-

a) Copper

b) Carbon

c) Phosphor bronze

d) Aluminium

Answer:- c) Phosphor bronze

46. In a hydro-electric plant a

conduct system for taking water

from the intake works to the
turbine is known as -

a) Dam

b) Reservoir

c) Penstock

d) Surge tank

Answer:- c) Penstock

47. The shaft of an induction

motor is made from -

a) High speed steel

b) Stainless steel

c) Carbon steel

d) Cast iron

Answer:- c) Carbon steel

48. In a induction motor,

no-load slip is generally -
a) Less than 1 percent

b) 5 percent

c) 2percenl .

d) 4 percent

Answer:- a) Less than

                    1 percent

49. The most common

type of ac motor is the -

a) Single phase induction

    motor

b) Two-phase induction

     motor

c) Three-phase induction

     motor

d) Two-phase squirrel-cage

    motor

Answer:- c) Three-phase

               induction motor

50. A single-phase induction

motor -

a) Is self-starting

b) Operates at a fixed speed

c) Is less reliable than a

three-phase synchronous motor

d) None of the above

Answer:- d) None of the above