[solved] 160 Instruments and Measurements Objective Questions

160 Instruments and Measurements MCQs with Answers

1. The use of _____ instruments is merely confined within laboratories as standardizing instruments.
(a) absolute
(b) indicating
(c) recording
(d) integrating
(e) none of the above
Ans: a



2. Which of the following instruments indicate the instantaneous value of the electrical quantity
being measured at the time at which it is being measured ?
(a) Absolute instruments
(b) Indicating instruments
(c) Recording instruments
(d) Integrating instruments
Ans: b

3. _____ instruments are those which measure the total quantity of electricity delivered in a
particular time.
(a) Absolute
(b) Indicating
(c) Recording
(d) Integrating
Ans: d

4. Which of the following are integrating instruments ?
(a) Ammeters
(b) Voltmeters
(c) Wattmeters
(d) Ampere-hour and watt-hour meters
Ans: d

5. Resistances can be measured with the help of
(a) wattmeters
(b) voltmeters
(c) ammeters
(d) ohmmeters and resistance bridges
(e) all of the above
Ans: d

6 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
7. Which of the following essential features is possessed by an indicating instrument ?
(a) Deflecting device
(b) Controlling device
(c) Damping device
(d) All of the above
Ans: d
8. 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
9. The spring material used in a spring control device should have the following property.
(a) Should be non-magnetic
(b) Most be of low temperature co-efficient
(c) Should have low specific resistance
(d) Should not be subjected to fatigue
(e) All of the above
Ans: e
10. Which of the following properties a damping oil must possess ?
(a) Must be a good insulator
(b) Should be non-evaporating
(c) Should not have corrosive action upon the metal of the vane
(d) The viscosity of the oil should not change with the temperature
(e) All of the above
Ans: e
11. A moving-coil permanent-magnet instrument can be used as _____ by using a low
resistance shunt.
(a) ammeter
(b) voltmeter
(c) flux-meter
(d) ballistic galvanometer
Ans: a
12. 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
13. Which of the following devices may be used for extending the range of instruments ?
(a) Shunts
(b) Multipliers
(c) Current transformers
(d) Potential transformers
(e) All of the above
Ans: e
14. An induction meter can handle current upto
(a) 10 A
(b) 30 A
(c) 60 A
(d) 100 A
Ans: d
15. 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
16. Induction type single phase energy meters measure electric energy in
(a) kW
(b) Wh
(c) kWh
(d) VAR
(e) None of the above
Ans: c
17. Most common form of A.C. meters met with in every day domestic and industrial
installations are
(a) mercury motor meters
(b) commutator motor meters
(c) induction type single phase energy meters
(d) all of the above
Ans: c
18. Which of the following meters are not used on D.C. circuits
(a) Mercury motor meters
(b) Commutator motor meters
(c) Induction meters
(d) None of the above
Ans: c
19. Which of the following is an essential part of a motor meter ?
(a) An operating torque system
(b) A braking device
(c) Revolution registering device
(d) All of the above
Ans: d
20. 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
21 is an instrument which measures the insulation resistance of an electric circuit relative to
earth and one another,
(a) Tangent galvanometer
(b) Meggar
(c) Current transformer
(d) None of the above
Ans: b
22. The household energy meter is
(a) an indicating instrument
(b) a recording instrument
(c) an integrating instrument
(d) none of the above
Ans: c
23. The pointer of an indicating instrument should be
(a) very light
(b) very heavy
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
24. The chemical effect of current is used in
(a) D.C. ammeter hour meter
(b) D.C. ammeter
(c) D.C. energy meter
(d) none of the above
Ans: a
25. In majority of instruments damping is provided by
(a) fluid friction
(b) spring
(c) eddy currents
(d) all of the above
Ans: c
26. An ammeter is a
(a) secondary instrument
(b) absolute instrument
(c) recording instrument
(d) integrating instrument
Ans: a
27. In a portable instrument, the controlling torque is provided by
(a) spring
(b) gravity
(c) eddy currents
(d) all of the above
Ans: a
28. The disc of an instrument using eddy current damping should be of
(a) conducting and magnetic material
(b) non-conducting and magnetic material
(c) conducting and non-magnetic material
(d) none of the above
Ans: c
29. The switch board instruments
(a) should be mounted in vertical position
(6) should be mounted in horizontal position
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
30. 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
31. The multiplier and the meter coil in a voltmeter are in
(a) series
(b) parallel
(c) series-parallel
(d) none of the above
Ans: a
32. A moving iron instrument can be used for
(a) D.C. only
(b) A.C. only
(c) both D.C. and A.C.
Ans: c
33. The scale of a rectifier instrument is
(a) linear
(b) non-linear
(c) either (a) or (b)
(d) neither (a) nor (b)
Ans: a
34. For measuring current at high frequency we should use
(a) moving iron instrument
(b) electrostatic instrument
(c) thermocouple instrument
(d) none of the above
Ans: c
35. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be
(a) almost zero
(b) low
(c) high
(d) none of the above
Ans: c
36. A dynamometer wattmeter can be used for
(a) both D.C. and A.C.
(b) D.C. only
(c) A.C. only
(d) any of the above
Ans: a
37. An induction wattmeter can be used for
(a) both D.C. and A.C.
(6) D.C. only
(c) A.C. only
(d) any of the above
Ans: b
38. 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
39. 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
40. 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
41. In a 3-phase power measurement by two wattmeter method, both the watt meters had
identical readings. The power factor of the load was
(a) unity
(6) 0.8 lagging
(c) 0.8 leading
(d) zero
Ans: a
42. In a 3-phase power measurement by two wattmeter method the reading of one of the
wattmeter was zero. The power factor of the load must be
(a) unity
(b) 0.5
(c) 0.3
(d) zero
Ans: b
43. The adjustment of position of shading bands, in an energy meter is done to provide
(a) friction compensation
(b) creep compensation
(c) braking torque
(d) none of the above
Ans: a
44. An ohmmeter is a
(a) moving iron instrument
(b) moving coil instrument
(c) dynamometer instrument
(d) none of the above
Ans: b
45. When a capacitor was connected to the terminal of ohmmeter, the pointer indicated a low
resistance initially and then slowly came to infinity position. This shows that capacitor is
(a) short-circuited
(b) all right
(c) faulty
Ans: b
46. For measuring a very high resistance we should use
(a) Kelvin's double bridge
(b) Wheat stone bridge
(c) Meggar
(d) None of the above
Ans: c
47. The electrical power to a meggar is provided by
(a) battery
(b) permanent magnet D.C. generator
(c) AC. generator
(d) any of the above
Ans: b
48. In a meggar controlling torque is provided by
(a) spring
(b) gravity
(c) coil
(d) eddy current
Ans: c
49. The operating voltage of a meggar is about
(a) 6 V
(b) 12 V
(c) 40 V
(d) 100 V
Ans: d
50. Murray loop test can be used for location of
(a) ground fault on a cable
(b) short circuit fault on a cable
(c) both the ground fault and the short-circuit fault
(d) none of the above
Ans: c
51. 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
52. 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
53. 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
54. 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
55. 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
56. A phase shifting transformer is used in conjunction with
(a) D.C. potentiometer
(b) Drysdale potentiometer
(c) A.C. co-ordinate potentiometer
(d) Crompton potentiometer
Ans: b
57. Basically a potentiometer is a device for
(a) comparing two voltages
(b) measuring a current
(c) comparing two currents
(d) measuring a voltage
(e) none of the above
Ans: a
58. 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
59. 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
60. 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
61. In an AC. co-ordinate potentiometer, the currents in the phase and quadrature
potentiometer are adjusted to be
(a) out of phase by 90°
(6) 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
62. A universal RLC bridge uses
(a) Maxwell bridge configuration for measurement of inductance and De Santas bridge for
measurement of capacitance
(b) Maxwell Wein bridge for measurement of inductance and modified De Santy's bridge for
measurement of capacitance
(c) Maxwell Wein bridge for measurement of inductance and Wein bridge for measurement of
capacitance
(d) Any of the above.
Ans: b
63. For measurements on high voltage capacitors, the suitable bridge is
(a) Wein bridge
(b) Modified De Santy's bridge
(c) Schering bridge
(d) Any of the above
(e) None of the above
Ans: c
64. In an Anderson bridge, the unknown inductance is measured in terms of
(a) known inductance and resistance
(b) known capacitance and resistance
(c) known resistance
(d) known inductance
Ans: b
65. 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
66. For measurement of mutual inductance we can use
(a) Anderson bridge
(b) Maxwell's bridge
(c) Heaviside bridge
(d) Any of the above
Ans: c
67. For measurement of inductance having high value, we should use
(a) Maxwell's bridge
(b) Maxwell Wein bridge
(c) Hay's bridge
(d) Any of the above
Ans: c
68. If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is
(a) 10°
(b) 80°
(c) 120°
(d) 170°
Ans: a
69. In a Schering bridge the potential of the detector above earth potential is
(a) a few volts only
(6) 1 kV
(c) 5 kV
(d) 10 kV
Ans: a
70. 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
71. 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
72. A power factor meter has
(a) one current circuit and two pres¬sure 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
73. 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
74. 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
75. 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
76. 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
77. 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
78. A Weston frequency meter is
(a) moving coil instrument
(b) moving iron instrument
(c) dynamometer instrument
(d) none of the above
Ans: b
79. A Weston synchronoscope is a
(a) moving coil instrument
(b) moving iron instrument
(c) dynamometer instrument
(d) none of the above
Ans: c
80. In a Weston synchronoscope, the fixed coils are connected across
(a) bus-bars
(b) incoming alternator
(c) a lamp
(d) none of the above
Ans: b
81. 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
82. The power factor of a single phase load can be calculated if the instruments available are
(a) one voltmeter and one ammeter
(b) one voltmeter, one ammetqr and one wattmeter
(c) one voltmeter, one ammeter and one energy meter
(d) any of the above
Ans: b
83. The desirable static characteristics of a measuring system are
(a) accuracy and reproducibility
(b) accuracy, sensitivity and reproducibility
(c) drift and dead zone
(d) static error
Ans: b
84. 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
85. Systematic errors are
(a) instrumental errors
(b) environmental errors
(c) observational errors
(d) all of the above
Ans: d
86. Standard resistor is made from
(a) platinum
(b) maganin
(c) silver
(d) nichrome
Ans: b
87. Commonly used standard capacitor is
(a) spherical type
(b) concentric cylindrical type
(c) electrostatic type
(d) multilayer parallel plate type
Ans: b
88. Operating torques in analogue instruments are
(a) deflecting and control
(b) deflecting and damping
(c) deflecting, control and damping
(d) vibration and balancing
Ans: c
89. Commonly used instruments in power system measurement are
(a) induction
(b) moving coil or iron
(c) rectifier
(d) electrostatic
Ans: a
90. 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
91. 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
92. Volt box is a component to
(a) extend voltage range
(6) measure voltage
(c) compare voltage in a box
(d) none of the above
Ans: a
93. 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
94. The gravity controlled instrument has crowded scale because current is proportional to
(a) balancing weight
(b) deflection angle
(c) sine of deflection angle
Ans: c
95. A sensitive galvanometer produces large deflection for a
(a) small value of current
(b) large value of current
(c) large value of power
(d) large value of voitage
(e) none of the above
Ans: a
96. A multirangq instrument has
(a) multiple shunt or series resistances inside the meter
(b) multicoii arrangement
(c) variable turns of coil
(d) multi range meters inside the measurement system
(e) any of the above
Ans: a
97. The rectifier instrument is not free from
(a) temperature error
(b) wave shape error
(c) frequency error
(d) all of the above
Ans: c
98. Alternating current is measured by
(a) induction ammeter
(b) permanent magnet type ammeter
(c) electrostatic ammeter
(d) moving iron repulsion type voltmeter
Ans: a
99. Most sensitive galvanometer is
(a) elastic galvanometer
(b) vibration galvanometer
(c) Duddlb galvanometer
(d) spot ballistic galvanometer
Ans: d
100. Instrument transformers are
(a) potential transformers
(b) current transformers
(c) both (a) and (b)
(d) power transformers
Ans: c
101. An instrument transformer is used to extend the range of
(a) induction instrument
(b) electrostatic instrument
(c) moving coil instrument
(d) any of the above
Ans: a
102. Wattmeter cannot be designed on the principle of
(a) electrostatic instrument
(b) thermocouple instrument
(c) moving iron instrument
(d) electrodynamic instrument
Ans: c
103. In an energymeter 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
104. Various adjustments in an energy meter include
(a) light load or friction
(b) lag and creep
(c) overload and voltage compensation
(d) temperature compensation
(e) all of the above
Ans: e
105. The power of a n-phase circuit can be measured by using a minimum of
(a) (n - 1) wattmeter elements
(b) n wattmeter elements
(c) (n + 1) wattmeter elements
(d) 2n wattmeter elements
Ans: a
106. Two holes in the disc of energymeter are drilled at the opposite sides of the spindle to
(a) improve its ventilation
(b) eliminate creeping at no load
(c) increase its deflecting torque
(d) increase its braking tcrque
Ans: b
107. Which of the following is measured by using a vector voltmeter ?
(a) Amplifier gain and phase shift
(b) Filler transfer functions
(c) Complex insersion loss
(d) All of the above
Ans: d
108. The principle on which vector voltmeter is based is
(a) that it works on the principle of complex variation
(b) that it measures the response of linear ramp voltage
(c) same as digital meter
(d) that it measures the amplitude of a single at two points and at the same time measures their
phase difference
Ans: d
109. To measure radio frequency, the suitable frequency meter is
(a) Weston frequency meter
(b) reed vibrator frequency meter
(c) hetrodyne frequency meter
(d) electrical resonance frequency meter
Ans: c
110. Hysteresis of an instrument means:
a) The change in the same reading when input is first increased and then decreased
b) The reliability of the instrument
c) The repeatability of the insrument
d) The inaccuracy due to change in temperature
ANSWER : A
111. In which part of the scale does the pointer indicate more accurately
a) In the first third of the cycle
b) In the first half of the cycle
c) In about middle of the scale
d) In the last third of the cycle
ANSWER : C
112. For measuring an unknown electrical quantity, select the meter with
a) Highest range and work down
b) Lowest range and work up
c) Middle range and can be work up or down depending
d) Any of the above
ANSWER : A
114. The ratio of maximum displacement deviation to the full scale deviation of the instrument is called:
a) Static sensitivity
b) Accuracy
c) Linearity
d) Precision
ANSWER : C
115. A 150 V moving iron voltmeter of accuracy class 1.0 reads 75 V when used in a circuit under a standard conditions. The maximum possible percentage error in the reading is:
a) 0.5
b) 1.0
c) 2.0
d) 4.0
ANSWER : C
116. The relative error is the:
a) Difference of the measured value and the true value
b) Ratio of absolute error to the measured value of the quantity under measurement
c) Ratio of the absolute error to the true value of the quantity under measurement
d) Ratio of the probable error to the true value of the quantity under measurment
ANSWER : C
117. The moving iron voltmeters are likely:
a) To indicate the same value of the ac as on dc
b) To indicate higher value of ac than on dc
c) To indicate lower value of ac than on dc
d) The moving iron instruments should not be used for dc measurment
ANSWER : C
118. The power measurement in a balanced 3-phase circuit can be done by:
a) One wattmeter method
b) Two wattmeter method
c) Three wattmeter method
d) Any of the above method
ANSWER : D
119. Anderson’s bridge is a modification of:
a) Maxwell’s wien bridge
b) Hay’s bridge
c) Schering bridge
d) Owen bridge
ANSWER : A
120. Ballastic tests are used in magnetic measurements for the determination of:
a) Flux density of the specimen
b) B-H curve of the specimen
c) Hysteresis loop of the specimen
d) All the above
ANSWER : D
121. Anderson Bridge is used to measure:
a) L
b) C
c) V
d) I
ANSWER : A
122. Hay’s Bridge is suitable for the measurement of:
a) Inductances with Q>10
b) Inductances with Q<10
c) Capacitors with high dissipation factor
d) Capacitors with low dissipation factor
ANSWER : A
123. The frequency can be measured by using:
a) Wien’s bridge
b) De Sauty’s bridge
c) Schering’s bridge
d) Anderson’s bidge
ANSWER : C
124. The ballistic galvanometer is usually lightly damped so that:
a) It may oscillate
b) It may remain stable
c) Amplitude of the first swing is large
d) Amplitude of the first swing is small
ANSWER : C
125. B-H Curve is used to determination of:
a) Hysteresis loss
b) Iron loss
c) Eddy current loss
d) Both (a) and (b)
ANSWER : A
126. Magnetic materials can be tested by:
a) Self inductance bridge
b) Cambell’s mutual inductance bridge
c) AC potentiometer
d) All the above
ANSWER : D
127. A PMMC instrument can be used as a fluxmeter by:
a) Using low resistance shunt
b) Removing the control spring
c) Making the control springs of large moment of inertia
d) Using a high series resistance
ANSWER : B
128. Open circuit fault in a cable can be located by:
a) Blavier’s test
b) Capacity test
c) Varley loop test
d) Murray loop test
ANSWER : B
129. In CRO the time base signal is applied to:
a) Y-plates
b) X-plates
c) Either X-plate or Y-plate
d) Both X-plate and Y-plate
ANSWER : B
130.In CRO astigmatism is:
a) Source of generating fast electrons
b) Media for absorbing secondary emission electrons
c) An additional focus control
d) Time-delay control in the vertical deflection system
ANSWER : C
131. The main advantage of crystal oscillator is that its output is:
a) A Constant frequency range
b) DC
c) 50 Hz to 60 Hz
d) Variable frequency
ANSWER : A
132. Which of the following statement is true of phase-shift type and Wien-bridge type R-C oscillators:
a) Both use positive feedback
b) The former uses positive feedback only whereas the latter uses both positive and negative feedback
c) The former uses both positive and negative feedback
d) Both use negative feedback
ANSWER : B
133. Moving iron and PMMC instruments can be distinguished from each other by looking at:
a) Pointer
b) Terminal size
c) Scale
d) Scale range
ANSWER : C
134. In a dynamo-meter type of moving coil instrument a swamping resistance is provided inorder to:
a) Control the deflection torque
b) Reduce the bulk of the moving system
c) Reduce the current flowing through the moving coil
d) Provide equal time constant for moving coil and fixed coil, when used for ac measurement
ANSWER : D
135. The deflection of hot-wire instrument depends on:
a) Instantaneous value of alternating current
b) Average value of current
c) RMS value of the alternating current
d) Voltage
ANSWER : C
136. If two meters X and Y requires 40mA and 50mA respectively, to give full scale deflection, then:
a) X is more sensitive
b) Y is more sensitive
c) Both X and Y are equally sensitive
d) It would not be possible to access the sensitivity on the basis of the given data
ANSWER : A
137. The reliability of the instrument refer to:
a) Measurement of changes due to temperature variations
b) Degree to which repeatability continues to remain within specified limits
c) The life of the instrument
d) The extent to which the characteristics remain linear
ANSWER : B
138. The damping torque must operate only when the moving system of the indicating instrument is:
a) Actually moving
b) Stationary
c) Just starting to move
d) Near its full deflection
ANSWER : A
139. If a voltmeter is connected, like an ammeter in series to the load:
a) The measurement reading will be too high
b) Almost no current will flow in the circuit
c) The meter will burn
d) An instantaneously high current will flow
ANSWER : B
130. Preferred material for permanent magnet is:
a) Stainless steel
b) Alnico
c) Tungsten steel
d) Soft iron
ANSWER : B
141. Air friction damping is used in the instruments which is:
a) Moving iron
b) Moving coil
c) Induction
d) Hot wire
ANSWER : A
142. PMMC instrument gives uniform scale because:
a) It uses spring control
b) It uses eddy current damping
c) The deflection torque is proportional to the instrument current
d) Both (a) and (c)
ANSWER : D
143.An instrument that is capable of measuring only dc is:
a) Moving coil
b) Moving iron
c) Thermo couple
d) None of the above
ANSWER : A
144. Maxwell-Wien bridge is used to measure:
a) Inductance
b) Capacitance
c) Dielectric loss
d) Frequency
ANSWER : A
145.A ballistic galvanometer is used to measure:
a) Charge
b) Current
c) Voltage
d) Frequency
ANSWER : A
146. ____ factor is the ratio of total flux to the useful flux in a magnetic circuit:
a) Form factor
b) Leakage
c) Utility
d) Dispersion
ANSWER : B
147. For eliminating the effect of earth capacitance from the bridge network we use:
a) Wagner’s earthing device
b) High voltage at low frequency
c) Low voltage at high frequency
d) Campbell-maxwell device
ANSWER : A
148. The most commonly used null deflector in a power frequency ac bridge is a:
a) Vibration galvanometer
b) D’Arsanval galvanometer
c) Ballistic galvanometer
d) Tachometer
ANSWER : A
149. For measuring emf of a standard cell we use:
a) Galvanometer
b) Potentiometer
c) Zener reference
d) Electro-dynamic voltmeter
ANSWER : B
150.Loss of charge method is used to measure:
a) Low R
b) High R
c) Low L
d) High L
ANSWER : B
151. Megger is an instrument used for the measurement of:
a) High resistance and insulation resistance
b) Medium resistance
c) Low resistance
d) Leakage current
ANSWER : A
152. Vibration reeds are employed in:
a) Frequency meter
b) Power factor meter
c) Synchroscope
d) Megger
ANSWER : A
153. Kelvin double bridge is best suited for the measurement of:
a) Inductance
b) Capacitance
c) Low resistance
d) High resistance
ANSWER : C
154. Introduction of dielectric:
a) Increases the capacitance
b) Reduces the breakdown voltage
c) Reduces the mechanical voltage
d) Increases the size of the capacitor
ANSWER : A
155. The material used to make standard resistance is:
a) Manganin
b) Aluminium
c) Nichrome
d) Platinum
ANSWER : A
156. Which of the following instruments have least torque/weight ratio:
a) Dynamometer type
b) PMMC
c) Attraction type moving iron
d) Repulsion type moving iron
ANSWER : A
157. The instrument having its deflection depends upon average value is:
a) Moving iron
b) Hot wire
c) Rectifier type
d) Induction type
ANSWER : C
158. Which of the following instruments can be used for full scale deflection of 300o:
a) PMMC
b) Induction type
c) Hot wire
d) Electrostatic
ANSWER : B

159.While testing cables the galvanometer used should be initially short-circuited in order to protect it from sudden initial inrush currents as the cable have:
a) A low value of initial resistance
b) A low value of initial capacitance
c) A high value of initial capacitance
d) Both (a) and (b)
ANSWER : C

160. A Ohmmeter is basically:
a) A ammeter
b) A voltmeter
c) A multimeter
d) None of the above

ANSWER : A