FEB 2018

ELECTRICIAN THEORY

SEMESTER-4

PART-2

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