Q51. The unit of power factor is:
A) Watt
B) Var
C) No unit (dimensionless)
D) Joule
Ans: C
Q52. Which of the following is a null type instrument?
A) Galvanometer
B) Potentiometer
C) Energy meter
D) Wattmeter
Ans: B
Q53. Which instrument uses a “swamping resistor”?
A) Ammeter
B) PMMC voltmeter
C) MI instrument
D) Energy meter
Ans: B
Q54. Which method is used to measure medium resistance?
A) Wheatstone bridge
B) Kelvin bridge
C) Megger
D) Voltmeter–ammeter method
Ans: A
Q55. Which instrument indicates instantaneous value?
A) Integrating type
B) Indicating type
C) Recording type
D) Null type
Ans: B
Q56. Which instrument records continuously with respect to time?
A) Recording type
B) Indicating type
C) Integrating type
D) Null type
Ans: A
Q57. The spring used in PMMC meter provides:
A) Controlling torque
B) Deflecting torque
C) Damping torque
D) Both controlling and damping torque
Ans: D
Q58. In a dynamometer wattmeter, the pressure coil is connected in:
A) Series with load
B) Parallel with load
C) Across current coil
D) Across supply
Ans: B
Q59. Phantom loading is used for testing:
A) Energy meters
B) Wattmeters
C) Galvanometers
D) Ammeters
Ans: A
Q60. Accuracy class of an instrument indicates:
A) Operating voltage
B) Precision of measurement
C) Range
D) Temperature effect
Ans: B
Q61. Which instrument uses damping torque produced by air friction?
A) Hot wire
B) Galvanometer
C) Energy meter
D) Electrostatic voltmeter
Ans: B
Q62. A CRO time base is generated by:
A) Sine wave
B) Sawtooth wave
C) Square wave
D) Triangular wave
Ans: B
Q63. A CRO beam is deflected by:
A) Magnetic field
B) Electrostatic field
C) Eddy current
D) Heating effect
Ans: B
Q64. In a PMMC meter, damping torque is provided by:
A) Eddy currents
B) Spring
C) Gravity
D) Friction
Ans: A
Q65. Instrument transformers are used for:
A) Extending range
B) Safety isolation
C) Easy metering
D) All of the above
Ans: D
Q66. Current transformer (CT) secondary should never be:
A) Shorted
B) Open circuited
C) Grounded
D) Loaded
Ans: B
Q67. Potential transformer (PT) is always connected:
A) Series with load
B) Parallel with load
C) Across CT
D) In series with CT
Ans: B
Q68. Power is measured in a 3-phase circuit by:
A) One wattmeter method
B) Two wattmeter method
C) Three wattmeter method
D) All of the above
Ans: D
Q69. In two wattmeter method, if readings are equal and opposite, the power factor is:
A) Unity
B) Zero
C) 0.5
D) 0.707
Ans: B
Q70. In a moving iron instrument, the deflection is proportional to:
A) Current
B) Current²
C) Voltage
D) Resistance
Ans: B
Q71. Which method is most accurate for calibration of voltmeter?
A) Potentiometer method
B) Ohm’s law method
C) Wattmeter method
D) Ammeter method
Ans: A
Q72. The frequency of AC supply can be measured by:
A) Energy meter
B) Synchroscope
C) Frequency meter
D) Both B and C
Ans: D
Q73. Which meter works on electrostatic principle?
A) Voltmeter
B) Wattmeter
C) Ammeter
D) Energy meter
Ans: A
Q74. Which type of error occurs due to personal habits?
A) Gross error
B) Systematic error
C) Random error
D) Instrumental error
Ans: A
Q75. The process of finding difference between true value and measured value is called:
A) Accuracy
B) Error
C) Precision
D) Sensitivity
Ans: B
Q76. The reciprocal of accuracy is:
A) Precision
B) Sensitivity
C) Relative error
D) Uncertainty
Ans: C
Q77. The range of an ammeter is extended by using:
A) Shunt
B) Multiplier
C) Swamping resistance
D) Series resistor
Ans: A
Q78. The range of a voltmeter is extended by using:
A) Shunt
B) Multiplier
C) Swamping resistance
D) Parallel resistor
Ans: B
Q79. Which instrument is free from hysteresis error?
A) MI
B) PMMC
C) Electrodynamometer
D) Induction type
Ans: B
Q80. Which meter measures reactive power?
A) Wattmeter
B) Var meter
C) Energy meter
D) Synchroscope
Ans: B
Q81. A power triangle relates:
A) Voltage, current, resistance
B) True, reactive, apparent power
C) P, V, I
D) Energy, time, frequency
Ans: B
Q82. The volt-ratio box is used with:
A) Ammeter
B) Galvanometer
C) Potentiometer
D) Energy meter
Ans: C
Q83. A flux meter measures:
A) Magnetic flux
B) Inductance
C) Capacitance
D) Resistance
Ans: A
Q84. Which bridge is used to measure capacitance of a cable?
A) Maxwell
B) Schering
C) Wien’s
D) Hay’s
Ans: B
Q85. Which instrument uses a pointer and calibrated scale?
A) Analog instrument
B) Digital instrument
C) Null type
D) CRO
Ans: A
Q86. Digital instruments have advantage of:
A) Less accuracy
B) More accuracy & speed
C) Higher power loss
D) Continuous pointer reading
Ans: B
Q87. LVDT is used to measure:
A) Voltage
B) Current
C) Displacement
D) Resistance
Ans: C
Q88. Which sensor is used in digital energy meters?
A) Electrodynamometer
B) Hall effect sensor
C) Moving iron
D) Hot wire
Ans: B
Q89. Which instrument has non-uniform scale?
A) MI instrument
B) PMMC instrument
C) Dynamometer wattmeter
D) CRO
Ans: A
Q90. The deflecting torque in induction type instruments is due to:
A) Heating effect
B) Eddy currents
C) Magnetic attraction
D) Electrostatics
Ans: B
Q91. A synchroscope measures:
A) Voltage
B) Frequency difference
C) Phase difference
D) Both B and C
Ans: D
Q92. Which is used for high-frequency measurement?
A) Hot-wire meter
B) PMMC meter
C) Moving iron meter
D) Dynamometer
Ans: A
Q93. A strain gauge measures:
A) Stress
B) Strain
C) Displacement
D) Power
Ans: B
Q94. True RMS meters are based on:
A) Average value
B) Heating effect
C) Peak value
D) Induction principle
Ans: B
Q95. Which instrument measures harmonics in waveform?
A) CRO
B) Spectrum analyzer
C) Wattmeter
D) Var meter
Ans: B
Q96. Which meter can measure very small currents accurately?
A) PMMC galvanometer
B) MI instrument
C) Hot wire instrument
D) Wattmeter
Ans: A
Q97. A digital voltmeter displays:
A) Pointer deflection
B) Digital number
C) Oscillations
D) None
Ans: B
Q98. Which type of instrument uses a soft iron vane?
A) PMMC
B) MI instrument
C) Electrostatic
D) Dynamometer
Ans: B
Q99. A CRO vertical amplifier controls:
A) Time base
B) Deflection sensitivity
C) Sweep speed
D) Triggering
Ans: B
Q100. Accuracy of a potentiometer is limited by:
A) Galvanometer sensitivity
B) Contact resistance
C) Wire uniformity
D) All of the above
Ans: D
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