Q.1

In order to achieve accuracy, the slide wire of a potentiometer should be

  • as long as possible
  • as short as possible
  • neither too long nor too short
  • very thin
Q.2

Assertion (A): CRO can be used to study waveshape accurately.

Reason (R): Input impedance of a CRO is very high.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.3

Two wattmeter method for 3 phase power measurement can be used only for

  • balanced loads
  • unbalanced loads
  • both balanced and unbalanced loads
  • star connected loads
Q.4

The advantage of LVDT over inductive bridge type transducer is that

  • it gives high output for small changes in core position
  • it can be used over a temperature range of - 265°C to 600°C
  • it can measure displacement of moving object
  • the error due to stray magnetic field is less
Q.5

Acoustic strain gauges

  • have good linearity of measurement
  • do not have long term stability
  • have a large range of measurement
  • have an accuracy range of 0.1-1% depending on environment
Q.6

A CT is used to feed current coils of wattmeter, energy meter, power factor meter and an ammeter. Then

  • all the coils are in series
  • all coils are in parallel
  • the coils are in series-parallel
  • either (a) or (b)
Q.7

In measurements using strain gauge, the dummy strain gauge is used to

  • compensate for resistance of strain gauge
  • compensate for change in temperature
  • compensate for error due to change in voltage of battery
  • compensate for error in voltmeter
Q.8

Which one of the following is true?

  • Alternating voltage and current contain odd and even harmonics
  • The inductance in a circuit reduces the effect of harmonics and makes current wave more sinusoidal than voltage wave
  • Alternating voltage and current waveforms, in general, do not contain odd harmonics
  • Inductance of a circuit does not alter wave shape at all
Q.9

An oscilloscope has an input impedance consisting of 1 MΩ andpF is parallel. A high impedance probe connected to input of this oscilloscope has aMΩ series resistance. ThisMΩ series resistance

  • may not be shunted
  • should be shunted by 2 pF capacitor
  • should be shunted by 20 pF capacitor
  • should be shunted by 200 pF capacitor
Q.10

Assertion (A): Damping in a vibration galvanometer is small.

Reason (R): Vibration galvanometer is a PMMC instrument.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.11

Four capacitors are in parallel. Their values are 36.3 μF, 3.μF, 34.μF andμF with an uncertainty of digit in the last place. The total capacitance in significant figures is

  • 75.0 μF
  • 75.0 ± 0.1 μF
  • 75.1 ± 0.1 μF
  • 75.002 ± 0.1 μF
Q.12

In measuring resistance using voltmeter and ammeter, the resistances of voltmeter and ammeter also affect the accuracy of measurement.

  • True
  • False
Q.13

LVDT is used to measure

  • displacement
  • pressure
  • temperature
  • any of the above
Q.14

The scale of PMMC instrument is linear.

  • True
  • False
Q.15

A coil resonates at 1 MHz with a resonating capacitance ofpF. AtpF, resonance is obtained with a resonating capacitor ofpF. The self capacitance of coil is

  • 12 pF
  • 24 pF
  • 30 pF
  • 72 pF
Q.16

In a Weston synchronoscope the deflecting torque is zero when

  • currents in fixed and moving coils are in phase
  • currents in fixed and moving coils are out of phase by 90°
  • currents in fixed and moving coils are out of phase by 60°
  • none of the above
Q.17

In an ac single phase energy meter, the potential coil is put on

  • both side limbs, of upper magnet
  • central limb of upper magnet
  • one side limb of upper magnet
  • either (a) or (b)
Q.18

The accuracy of a multimeter is about

  • ± 3%
  • ± 0.5%
  • ± 0.01%
  • ± 10%
Q.19

Crompton potentiometer has

  • 14 coils and a slide wire all having the same resistance
  • 14 coils and a slide wire but the resistance of slide wire is half that of each coil
  • 14 coils each of different resistance
  • 14 coils out of which 7 coils have resistance which is twice that of remaining 7 coils
Q.20

In a CRO the Y plates are oriented

  • horizontally
  • vertically
  • at an angle of 20° of horizontal
  • at an angle of 70° of horizontal
Q.21

To measure moisture in wood, the most suitable method is

  • electric conduction
  • electrical-capacitive
  • absorption of radiation
  • equilibrium-moisture Vs humidity
Q.22

A Weston frequency meter is

  • moving coil instrument
  • moving iron instrument
  • dynamometer instrument
  • induction instrument
Q.23

Which of the following combinations is not used in thermocouple transducer measurement of temperature?

  • Iron-constantan
  • Chromel-aluminium
  • Copper-constantan
  • Iron-silver
Q.24

The dynamic characteristics of capacitive transducer are similar to those of

  • LP filter
  • HP filter
  • notch filter
  • band stop filter
Q.25

Which of the following is used as detector in audio frequency ac bridges?

  • AC voltmeter
  • CRO
  • Head phones
  • Vibration galvanometer
Q.26

Assertion (A): The gall tinsley potentiometer is a coordinate potentiometer and has two exactly similar potentiometers.

Reason (R): An ac potentiometer may measure the unknown voltage in polar form or rectangular coordinate form.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.27

Assertion (A): Thermistors are commonly used to measure hot spot temperatures in electric machines.

Reason (R): Thermistor has the advantages of high temperature coefficient, small size and high speed of response.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.28

A peak responding ac voltmeter using a half wave rectifier has been calibrated to read 1 V for 1 V rms sine wave input. If input is 1 V dc the reading will be

  • 0.707 V
  • 0.707 or 0 V
  • 1.414 V
  • 1.414 or 0 V
Q.29

Assertion (A): Megger is used to check insulation resistance of cables.

Reason (R): Insulation resistance of cables is very high.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.30

The chemical effect of current is used in

  • dc ampere hour meter
  • dc ammeter
  • ac energy meter
  • all of the above
Q.31

The output of a Piezoelectric crystal has

  • low amplitude and low impedance
  • high amplitude and low impedance
  • low amplitude and high impedance
  • high amplitude and high impedance
Q.32

Induction wattmeter is an absolute instrument.

  • True
  • False
Q.33

In a current transformers

  • the number of turns in primary and secondary windings are nearly equal
  • the number of primary turns is very small as compared to number of secondary turns.
  • the number of secondary turns is very small as compared to the number of primary turns
  • either (a) or (c).
Q.34

Assertion (A): For best results the system of a D'Arsonval galvanometer should be slightly under damped.

Reason (R): Degree of damping affects the time taken by the instrument to come to final position.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.35

The accuracy of an instrument is determined by

  • closeness of indicated value to the actual value
  • repeatability of measured value
  • speed with which the reading approaches final value
  • least value which can be measured
Q.36

If σ standard deviation, probable error

  • σ
  • ± 1.19 σ
  • ± 0.6745 σ
  • ± 0.4125 σ
Q.37

An E transformer is a

  • displacement transducer
  • velocity transducer
  • acceleration transducer
  • pressure transducer
Q.38

TheMHz in the specification of CRO means that

  • the sweep frequency is 10 MHz
  • the frequency of input signal should not be more than 10 MHz
  • the vertical amplifier has been designed for 10 MHz
  • none of the above
Q.39

Rayleigh current balance is an absolute instrument.

  • True
  • False
Q.40

The electrical power to a megger is provided by

  • battery
  • inverter
  • permanent magnet dc generator
  • ac generator
Q.41

DC voltage of the order of a few mV can be accurately of measured by

  • PMMC voltmeters
  • moving iron voltmeter
  • null balancing potentiometer
  • electrostatic voltmeter
Q.42

Absolute instruments are used in

  • laboratories
  • industries
  • power houses
  • standard laboratories
Q.43

For measuring inductance with high Q, we should use

  • Maxwell's bridge
  • Maxwell Wien bridge
  • Hay's bridge
  • Either (a) or (b)
Q.44

A resistance strain gauge has a resistance of about

  • 100 Ω
  • 25 Ω
  • 10 Ω
  • 1 Ω
Q.45

Assertion (A): A power factor meter operates on dynamometer principle.

Reason (R): A power factor meter does not have a control spring.

  • Both A and R are true and R is correct explanation of A
  • Both A and R are true but R is not correct explanation of A
  • A is true R is false
  • A is false R is true
Q.46

The pressure coil of a wattmeter should be connected to the supply side of the current coil when

  • load impedance in high
  • load impedance is low
  • voltage is high
  • voltage is low
Q.47

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

  • 0.25 Hz
  • 0.5 Hz
  • 1.25 Hz
  • 1 Hz
Q.48

The time base of a high frequency CRO whose screen diameter iscm is set atμ sec/cm. The lowest frequency which can be fully displayed on the screen is

  • more than 100 kHz
  • equal to 100 kHz
  • equal to 10 kHz
  • less than 10 kHz
Q.49

Eddy currents are essential for the deflecting torque of an induction wattmeter.

  • True
  • False
Q.50

The torque in induction wattmeters due to

  • capacitive current
  • electrostatic effect
  • hall effect
  • eddy currents
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