Measurement and Instrumentation MCQ Quiz - Multiple Choice Questions & Answers Page 3

21. In a portable instrument, the controlling torque is provided by

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

22. In a Schering bridge the potential of the detector above earth potential is

1. a few volts only
2. 1 kV
3. 5 kV
4. 10 kV

23. In a single phase power factor meter the phase difference between the currents in the two pressure coils is

1. exactly 0°
2. approximately 0°
3. exactly 90°
4. approximately 90°

24. In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of

1. 0.1 Hz
2. 0.25 Hz
3. 0.5 Hz
4. 1.5 Hz

25. In a Weston frequency meter, the magnetic axes of the two fixed coils are

1. parallel
2. perpendicular
3. inclined at 60°
4. inclined at 120°

26. In a Weston synchronoscope, the fixed coils are connected across

1. bus-bars
2. incoming alternator
3. a lamp
4. none of the above

27. 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°

28. 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

29. In an energymeter 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

30. In majority of instruments damping is provided by

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