The advantage of hot-wire instrument is

 

 ELECTRICAL AND ELECTRONIC MEASUREMENTS (MODERATE LEVEL)

Q1. The sensitivity of a voltmeter is defined as
A) Current per volt
B) Volt per ampere
C) Resistance per volt
D) Deflection per volt
Answer: C

Q2. The accuracy class 0.2 instrument means
A) 0.2% of full-scale error
B) 2% of measured value
C) 0.2% of measured value
D) ±0.2 V error always
Answer: A

Q3. The deflecting torque in PMMC instrument is proportional to
A) Current
B) Square of current
C) Magnetic flux
D) Voltage
Answer: A

Q4. The moving iron instrument can measure
A) Only DC
B) Only AC
C) Both AC and DC
D) None
Answer: C

Q5. The damping torque in a PMMC is produced by
A) Eddy currents
B) Air friction
C) Magnetic field
D) Spring control
Answer: A

Q6. The scale of a moving iron instrument is
A) Uniform
B) Non-uniform
C) Linear
D) Logarithmic
Answer: B

Q7. The control torque in a moving coil instrument is provided by
A) Spring
B) Air friction
C) Magnetic field
D) Gravity
Answer: A

Q8. A ballistic galvanometer is used to measure
A) Quantity of charge
B) Current
C) Power
D) Resistance
Answer: A

Q9. A dynamometer type wattmeter can measure
A) DC power only
B) AC power only
C) Both AC and DC power
D) Reactive power only
Answer: C

Q10. The torque in a dynamometer wattmeter is proportional to
A) VIcosφ
B) VI
C) I²
D) V²
Answer: A

Q11. In a 3-phase system, power factor =
A) (W₁ + W₂)/√3VLIL
B) cos⁻¹[(W₁−W₂)/(W₁+W₂)]
C) tan⁻¹(W₁/W₂)
D) None
Answer: B

Q12. The reading of both wattmeters are equal in a balanced 3-phase system when
A) pf = 1
B) pf = 0
C) pf = 0.5
D) pf = 0.866
Answer: A

Q13. If one wattmeter reads zero, the power factor is
A) 0
B) 0.5
C) 0.866
D) 1
Answer: C

Q14. The wattmeter’s potential coil should have
A) High resistance
B) Low resistance
C) Medium resistance
D) None
Answer: A

Q15. The current coil of wattmeter should have
A) Low resistance
B) High resistance
C) Zero resistance
D) Medium resistance
Answer: A

Q16. The damping in MI instruments is provided by
A) Air friction
B) Eddy current
C) Fluid damping
D) Magnetic field
Answer: A

Q17. The main error in PMMC instruments is due to
A) Weakening of permanent magnet
B) Eddy currents
C) Spring friction
D) Pointer weight
Answer: A

Q18. The torque to weight ratio of PMMC instrument is
A) High
B) Low
C) Medium
D) Constant
Answer: A

Q19. A thermocouple type instrument is suitable for measuring
A) AC current
B) DC current
C) Both
D) None
Answer: A

Q20. The operating principle of a thermocouple is based on
A) Seebeck effect
B) Hall effect
C) Peltier effect
D) Thomson effect
Answer: A

Q21. The instrument used to measure insulation resistance is
A) Megger
B) Multimeter
C) Ohmmeter
D) Wattmeter
Answer: A

Q22. In a megger, the voltage is generated by
A) Hand-driven generator
B) Battery
C) Transformer
D) None
Answer: A

Q23. The Kelvin double bridge is used to measure
A) Low resistance
B) High resistance
C) Medium resistance
D) Capacitance
Answer: A

Q24. The Schering bridge is used for
A) Capacitance measurement
B) Inductance measurement
C) Resistance measurement
D) Frequency measurement
Answer: A

Q25. The Maxwell bridge is used for
A) Inductance measurement
B) Capacitance measurement
C) Frequency
D) Resistance
Answer: A

Q26. The Wien bridge is used to measure
A) Frequency
B) Capacitance
C) Inductance
D) Resistance
Answer: A

Q27. A potentiometer measures voltage by
A) Comparing unknown emf with standard emf
B) Deflection method
C) Amplifying current
D) None
Answer: A

Q28. The main advantage of potentiometer is
A) No power drawn from circuit
B) Fast response
C) Compact size
D) Can measure AC directly
Answer: A

Q29. A digital multimeter eliminates
A) Parallax error
B) Accuracy
C) Loading effect
D) None
Answer: A

Q30. The resolution of a digital instrument is decided by
A) Number of digits
B) Range
C) Input impedance
D) Display type
Answer: A

Q31. The input impedance of a digital voltmeter is
A) Very high
B) Very low
C) Medium
D) Zero
Answer: A

Q32. The quantization error occurs in
A) Digital instruments
B) Analog instruments
C) Both
D) None
Answer: A

Q33. A sample and hold circuit is used in
A) ADC
B) DAC
C) Amplifier
D) Comparator
Answer: A

Q34. A dual-slope ADC is preferred for
A) High accuracy and noise rejection
B) High speed
C) Low cost
D) Simple design
Answer: A

Q35. The function of the time base generator in a CRO is to
A) Produce sawtooth voltage
B) Produce square wave
C) Amplify input
D) Synchronize trigger
Answer: A

Q36. The electron beam in a CRO is deflected by
A) Electric and magnetic fields
B) Only magnetic field
C) Only electric field
D) None
Answer: A

Q37. Lissajous pattern on CRO is used to measure
A) Phase difference
B) Current
C) Voltage
D) Resistance
Answer: A

Q38. The sensitivity of a CRO is measured in
A) V/cm
B) V/m
C) A/V
D) Ω/V
Answer: A

Q39. The RMS value of AC voltage is measured by
A) True RMS meter
B) Average responding meter
C) PMMC
D) None
Answer: A

Q40. The “form factor” of a waveform is defined as
A) RMS value / Average value
B) Average / RMS
C) Peak / RMS
D) RMS / Peak
Answer: A

Q41. For a sine wave, form factor =
A) 1.11
B) 1.414
C) 0.707
D) 1.0
Answer: A

Q42. For a sine wave, peak factor =
A) 1.414
B) 1.11
C) 0.707
D) 1.0
Answer: A

Q43. The Q-factor of a coil is
A) ωL/R
B) R/ωL
C) 1/ωL
D) ωR/L
Answer: A

Q44. A thermistor has
A) Negative temperature coefficient
B) Positive temperature coefficient
C) Constant resistance
D) Zero coefficient
Answer: A

Q45. The principle of LVDT is
A) Mutual induction
B) Self-induction
C) Capacitance
D) Resistance
Answer: A

Q46. The output of LVDT is
A) AC voltage proportional to displacement
B) DC voltage
C) Current
D) Resistance
Answer: A

Q47. The strain gauge works on
A) Variation of resistance with strain
B) Capacitance
C) Induction
D) Voltage
Answer: A

Q48. The gauge factor of strain gauge =
A) (ΔR/R) / Strain
B) (R/ΔR) × Strain
C) Strain × Resistance
D) None
Answer: A

Q49. The Hall effect is used to measure
A) Magnetic field
B) Pressure
C) Force
D) Current
Answer: A

Q50. The piezoelectric transducer converts
A) Pressure into voltage
B) Voltage into pressure
C) Temperature into current
D) Current into voltage
Answer: A

Q51. A bridge is balanced when
A) Detector shows zero
B) Shows maximum
C) Shows deflection
D) None
Answer: A

Q52. An Anderson bridge is used to measure
A) Inductance
B) Capacitance
C) Resistance
D) Frequency
Answer: A

Q53. The condition for bridge balance is
A) Product of opposite arms equal
B) Sum of arms equal
C) Product of adjacent arms equal
D) None
Answer: A

Q54. A CRO is mainly used for
A) Displaying waveform
B) Measuring power
C) Measuring energy
D) Controlling current
Answer: A

Q55. The advantage of digital instruments is
A) No parallax error
B) High accuracy
C) Compact
D) All of these
Answer: D

Q56. The analog instrument is better for
A) Continuously varying signals
B) Digital signals
C) High speed
D) Storage
Answer: A

Q57. The function of control springs is
A) Provide controlling torque
B) Provide damping
C) Provide indication
D) Provide restoring torque
Answer: A

Q58. The zero adjustment in PMMC is done by
A) Moving control springs
B) Adjusting coil
C) Changing magnet
D) Pointer length
Answer: A

Q59. An error due to temperature change is known as
A) Drift
B) Zero error
C) Parallax error
D) Random error
Answer: A

Q60. Systematic errors are
A) Constant or predictable
B) Random
C) Due to observer
D) None
Answer: A

Q61. The loading effect of a voltmeter can be reduced by
A) Increasing internal resistance
B) Decreasing internal resistance
C) Adding shunt
D) None
Answer: A

Q62. The main cause of damping in moving iron instruments is
A) Air friction
B) Eddy currents
C) Coil resistance
D) Pointer mass
Answer: A

Q63. A power factor meter measures
A) Power factor
B) Voltage
C) Phase difference
D) Both A & C
Answer: D

Q64. An energy meter works on the principle of
A) Electromagnetic induction
B) Electrostatic attraction
C) Heating effect
D) Eddy current
Answer: A

Q65. The speed of an energy meter is proportional to
A) Power
B) Voltage
C) Current
D) Power factor
Answer: A

Q66. Creeping in energy meter is
A) Slow continuous rotation at no-load
B) Excess speed
C) Magnetic drift
D) Load unbalance
Answer: A

Q67. Creeping is avoided by
A) Drilling two holes in disc
B) Increasing weight
C) Adding shunt
D) Increasing magnet
Answer: A

Q68. The braking torque in energy meter is proportional to
A) Speed
B) Speed²
C) 1/Speed
D) Voltage
Answer: A

Q69. The permanent magnet in an energy meter provides
A) Braking torque
B) Driving torque
C) Control torque
D) Deflection
Answer: A

Q70. The speed of energy meter disc is adjusted by
A) Brake magnet position
B) Spring tension
C) Pointer weight
D) None
Answer: A

Q71. The constant of energy meter is
A) Revolutions per kWh
B) Volts per amp
C) Ohms per watt
D) None
Answer: A

Q72. The creeping test is done to check
A) Low load error
B) High load error
C) Speed
D) Calibration
Answer: A

Q73. The overload test on energy meter checks
A) Stability
B) Durability
C) Accuracy at high load
D) Frequency
Answer: C

Q74. An electrostatic voltmeter is suitable for
A) High voltage
B) Low voltage
C) Both
D) None
Answer: A

Q75. The true RMS reading meter uses
A) Thermocouple
B) Rectifier
C) Amplifier
D) None
Answer: A

Q76. The magnetic loss in instruments increases with
A) Frequency
B) Voltage
C) Temperature
D) None
Answer: A

Q77. The calibration curve represents
A) Relation between true and measured value
B) Power factor
C) Deflection
D) Resistance
Answer: A

Q78. A bridge is called “AC bridge” when
A) It measures impedance
B) It works on DC
C) It measures voltage
D) None
Answer: A

Q79. The basic function of a galvanometer in bridge is to
A) Detect null
B) Indicate deflection
C) Measure resistance
D) Amplify signal
Answer: A

Q80. The frequency of AC supply affects
A) Inductive and capacitive bridges
B) Only resistive bridges
C) None
D) DC circuits
Answer: A

Q81. A low resistance is measured using
A) Kelvin bridge
B) Wheatstone bridge
C) Maxwell bridge
D) Schering bridge
Answer: A

Q82. The working principle of hot-wire instrument is
A) Heating effect of current
B) Magnetic effect
C) Induction
D) Capacitance
Answer: A

Q83. The advantage of hot-wire instrument is
A) Measures AC and DC
B) Measures only AC
C) Low cost
D) Linear scale
Answer: A

Q84. Thermocouple instruments are free from
A) Frequency errors
B) Phase error
C) Temperature error
D) Waveform error
Answer: D

Q85. The instrument transformer used for current measurement is
A) CT
B) PT
C) Both
D) None
Answer: A

Q86. The ratio of rated primary current to rated secondary current in a CT is called
A) Current ratio
B) Transformation ratio
C) Turns ratio
D) Burden
Answer: B

Q87. The burden of a CT is measured in
A) VA
B) W
C) A
D) Ω
Answer: A

Q88. The secondary of CT should never be
A) Open-circuited
B) Short-circuited
C) Loaded
D) Grounded
Answer: A

Q89. The secondary of a PT should never be
A) Short-circuited
B) Open-circuited
C) Grounded
D) Loaded
Answer: A

Q90. The polarity marks in CT/PT are used for
A) Proper connection
B) Reduce loss
C) Safety
D) None
Answer: A

Q91. The standard secondary current of a CT is
A) 5 A
B) 1 A
C) Both A and B
D) 10 A
Answer: C

Q92. The phase angle error in CT is
A) Phase difference between primary and secondary current
B) Voltage error
C) Power factor error
D) None
Answer: A

Q93. The instrument error due to stray fields can be minimized using
A) Magnetic shielding
B) Plastic casing
C) Larger meter
D) None
Answer: A

Q94. In AC bridges, balance condition is independent of
A) Supply frequency
B) Supply voltage
C) Capacitance
D) Resistance
Answer: B

Q95. The sensitivity of a galvanometer depends on
A) Strength of magnet
B) Coil turns
C) Current
D) All
Answer: D

Q96. The control torque is directly proportional to
A) Angle of deflection
B) Square of current
C) Voltage
D) Flux
Answer: A

Q97. The standard resistors are made of
A) Manganin
B) Copper
C) Aluminum
D) Nickel
Answer: A

Q98. An analog multimeter uses
A) Moving coil meter
B) LED display
C) CRT
D) None
Answer: A

Q99. The major limitation of analog instruments is
A) Parallax error
B) Cost
C) Power loss
D) None
Answer: A

Q100. The main advantage of electronic instruments is
A) High input impedance
B) Small size
C) High sensitivity
D) All of the above
Answer: D