Measurement and Instrumentation

51. In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be

1. out of phase by 90°
2. out of phase by 60°
3. out of phase by 30°
4. out of phase by 0°

View answer

52. In an Anderson bridge, the unknown inductance is measured in terms of

1. known inductance and resistance
2. known capacitance and resistance
3. known resistance
4. known inductance

View answer

53. In an energy meter braking torque is produced to

1. safe guard it against creep
2. brake the instrument
3. bring energy meter to stand still
4. maintain steady speed and equal to driving torque

View answer

54. In majority of instruments damping is provided by

1. fluid friction
2. spring
3. eddy currents
4. all of the above

View answer

55. In order to achieve high accuracy, the slide wire of a potentiometer should be

1. as long as possible
2. as short as possible
3. neither too small not too large
4. very thick

View answer

56. In Weston synchronoscope the moving coil is connected across

1. bus-bars
2. incoming alternator
3. fixed coils
4. any of the above

View answer

57. Induction type single phase energy meters measure electric energy in

1. kW
2. Wh
3. kWh
4. VAR

View answer

58. It is required to measure the true open circuit e.m.f. of a battery. The best device is

1. D.C. voltmeter
2. Ammeter and a known resistance
3. D.C. potentiometer
4. None of the above

View answer

59. Most common form of A.C. meters met with in every day domestic and industrial installations are

1. mercury motor meters
2. commutator motor meters
3. induction type single phase energy meters
4. all of the above

View answer

60. Most sensitive galvanometer is

1. elastic galvanometer
2. vibration galvanometer
3. Duddlb galvanometer
4. spot ballistic galvanometer

View answer