Multiple Choice Questions (MCQ) on Measurement and Instrumentation for Electrical Engineering
1. According to application, instruments are classified as
(a) switch board
(b) portable
(c) both (a) and (b)
(d) moving coil
(e) moving iron
(f) both (d) and (e)
Ans: c
2. A _____ device prevents the oscillation of the moving system and enables the latter to reach its final position quickly
(a) deflecting
(b) controlling
(c) damping
(d) any of the above
Ans: c
3. A moving-coil permanent-magnet instrument can be used as flux-meter
(a) by using a low resistance shunt
(b) by using a high series resistance
(c) by eliminating the control springs
(d) by making control springs of large moment of inertia
Ans: c
4. An induction meter can handle current up to
(a) 10 A
(b) 30 A
(c) 60 A
(d) 100 A
Ans: d
5. For handling greater currents induction wattmeters are used in conjunction with
(a) potential transformers
(b) current transformers
(c) power transformers
(d) either of the above
(e) none of the above
Ans: b
6. A potentiometer may be used for
(a) measurement of resistance
(b) measurement of current
(c) calibration of ammeter
(d) calibration of voltmeter
(e) all of the above
Ans: e
7. In majority of instruments, damping is provided by
(a) fluid friction
(b) spring
(c) eddy currents
(d) all of the above
Ans: c
8. In a portable instrument, the controlling torque is provided by
(a) spring
(b) gravity
(c) eddy currents
(d) all of the above
Ans: a
9. The switch board instruments
(a) should be mounted in vertical position
(b) should be mounted in horizontal position
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
10. The function of shunt in an ammeter is to
(a) by pass the current
(b) increase the sensitivity of the ammeter
(c) increase the resistance of ammeter
(d) none of the above
Ans: a
11. The pressure coil of a wattmeter should be connected on the supply side of the current coil when (a) load impedance is high
(b) load impedance is low
(c) supply voltage is low
(d) none of the above
Ans: a
12. In a low power factor wattmeter the pressure coil is connected
(a) to the supply side of the current coil
(b) to the load side of the current coil
(c) in any of the two meters at connection
(d) none of the above
Ans: b
13. In a low power factor wattmeter the compensating coil is connected
(a) in series with current coil
(b) in parallel with current coil
(c) in series with pressure coil
(d) in parallel with pressure coil
Ans: c
14. An ohmmeter is a
(a) moving iron instrument
(b) moving coil instrument
(c) dynamometer instrument
(d) none of the above
Ans: b
15. Which of the following devices should be used for accurate measurement of low D.C. voltage ? (a) Small range moving coil voltmeter
(b) D.C. potentiometer
(c) Small range thermocouple voltmeter
(d) None of the above
Ans: b
16. It is required to measure the true open circuit e.m.f. of a battery. The best device is
(a) D.C. voltmeter
(b) Ammeter and a known resistance
(c) D.C. potentiometer
(d) None of the above
Ans: c
17. A voltage of about 200 V can be measured
(a) directly by a D.C. potentiometer
(b) a D.C. potentiometer in conjunction with a volt ratio box
(c) a D.C. potentiometer in conjunction with a known resistance
(d) none of the above
Ans: b
18. A direct current can be measured by
(a) a D.C. potentiometer directly
(b) a D.C. potentiometer in conjunction with a standard resistance
(c) a D.C. potentiometer in conjunction with a volt ratio box
(d) none of the above
Ans: b
19. To measure a resistance with the help of a potentiometer it is
(a) necessary to standardise the potentiometer
(b) not necessary to standardise the potentiometer
(c) necessary to use a volt ratio box in conjunction with the potentiometer
(d) none of the above
Ans: b
20. In order to achieve high accuracy, the slide wire of a potentiometer should be
(a) as long as possible
(b) as short as possible
(c) neither too small not too large
(d) very thick
Ans: a
21. To measure an A. C. voltage by using an A.C. potentiometer, it is desirable that the supply for the potentiometer in taken
(a) from a source which is not the same as the unknown voltage
(b) from a battery
(c) from the same source as the unknown voltage
(d) any of the above
Ans: c
22. The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a
(a) single-phase winding
(b) two-phase winding
(c) three-phase winding
(d) any of the above
Ans: b
23. In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be
(a) out of phase by 90°
(b) out of phase by 60°
(c) out of phase by 30°
(d) out of phase by 0°
(e) out of phase by 180°
Ans: a
24. Wagner earthing device is used to eliminate errors due to
(a) electrostatic coupling
(b) electromagnetic coupling
(c) both (a) and (b)
(d) none of the above
Ans: a
25. In a Schering bridge the potential of the detector above earth potential is
(a) a few volts only
(b) 1 kV
(c) 5 kV
(d) 10 kV
Ans: a
26. To avoid the effect of stray magnetic field in A.C. bridges we can use
(a) magnetic screening
(b) Wagner earthing device
(c) wave filters
(d) any of the above
Ans: a
27. If an inductance is connected in one arm of bridge and resistances in the remaining three arms
(a) the bridge can always be balanced
(b) the bridge cannot be balanced
(c) the bridge can be balanced if the resistances have some specific values
Ans: b
28. A power factor meter has
(a) one current circuit and two pressure circuits
(b) one current circuit and one pressure circuit
(c) two current circuits and one pres¬sure circuit
(d) none of the above
Ans: a
29. The two pressure coils of a single phase power factor meter have
(a) the same dimensions and the same number of turns
(b) the same dimension but different number of turns
(c) the same number of turns but different dimensions
(d) none of the above
Ans: a
30. In a single phase power factor meter the phase difference between the currents in the two pressure coils is
(a) exactly 0°
(b) approximately 0°
(c) exactly 90°
(d) approximately 90°
Ans: c
31. In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at
(a) 0°
(b) 60°
(c) 90°
(d) 120°
Ans: d
32. In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of
(a) 0.1 Hz
(b) 0.25 Hz
(c) 0.5 Hz
(d) 1.5 Hz
Ans: c
33. In a Weston frequency meter, the magnetic axes of the two fixed coils are
(a) parallel
(b) perpendicular
(c) inclined at 60°
(d) inclined at 120°
Ans: b
34. A Weston frequency meter is
(a) moving coil instrument
(b) moving iron instrument
(c) dynamometer instrument
(d) none of the above
Ans: b
35. A Weston synchronoscope is a
(a) moving coil instrument
(b) moving iron instrument
(c) dynamometer instrument
(d) none of the above
Ans: c
36. In Weston synchronoscope, the moving coil is connected across
(a) bus-bars
(b) incoming alternator
(c) fixed coils
(d) any of the above
Ans: a
37. The ratio of maximum displacement deviation to full scale deviation of the instrument is called (a) static sensitivity
(b) dynamic deviation
(c) linearity
(d) precision or accuracy
Ans: c
38. Systematic errors are
(a) instrumental errors
(b) environmental errors
(c) observational errors
(d) all of the above
Ans: d
39. Commonly used standard capacitor is
(a) spherical type
(b) concentric cylindrical type
(c) electrostatic type
(d) multilayer parallel plate type
Ans: b
40. Commonly used instruments in power system measurement are
(a) induction
(b) moving coil or iron
(c) rectifier
(d) electrostatic
Ans: a
41. Damping of the Ballistic galvanometer is made small to
(a) get first deflection large
(b) make the system oscillatory
(c) make the system critically damped
(d) get minimum overshoot
Ans: a
42. If an instrument has cramped scale for larger values, then it follows
(a) square law
(b) logarithmic law
(c) uniform law
(d) none of the above
Ans: b
43. Volt box is a component to
(a) extend voltage range
(b) measure voltage
(c) compare voltage in a box
(d) none of the above
Ans: a
44. E.m.f. of a Weston cell is accurately measured by
(a) electrostatic voltmeter
(b) hot wire voltmeter
(c) isothermal voltmeter
(d) electrodynamic voltmeter
Ans: a
45. The rectifier instrument is not free from
(a) temperature error
(b) wave shape error
(c) frequency error
(d) all of the above
Ans: c
46. Wattmeter cannot be designed on the principle of
(a) electrostatic instrument
(b) thermocouple instrument
(c) moving iron instrument
(d) electrodynamic instrument
Ans: c
47. In an energy meter braking torque is produced to
(a) safe guard it against creep
(b) brake the instrument
(c) bring energy meter to stand still
(d) maintain steady speed and equal to driving torque
Ans: d
48. To measure radio frequency, the suitable frequency meter is
(a) Weston frequency meter
(b) reed vibrator frequency meter
(c) heterodoxy frequency meter
(d) electrical resonance frequency meter
Ans: c
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