# Measurements and Instrumentation MCQ Questions & Answers

Measurements and Instrumentation MCQs : This section focuses on the "Measurements and Instrumentation". These Multiple Choice Questions (MCQs) should be practiced to improve the Measurements and Instrumentation skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

Assertion (A): A p-n junction has high resistance in reverse direction.Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true

Question 2

A digital voltmeter has a read out range from 0 to 999 counts. If the full scale reading is 9.999 V, the resolution is

A. 1 V
B. 0.01 V
C. 1 mV
D. 1 μV

Question 3

An LVDT is used to measure displacement. The LVDT feeds a Voltmeter of 0-5 V range through a 250 gain amplifier. For a displacement 0.5 mm the output of LVDT is 2 mV. The sensitivity of instrument is

A. 0.1 V/mm
B. 0.5 V/mm
C. 1 V/mm
D. 5 V/mm

Question 4

A meter with a resistance of 100 Ω and a full scale deflection of current of 1 mA is to be converted into voltmeter of 0 - 5 V range. The multiplier resistance should be

A. 490 Ω
B. 5000 Ω
C. 4900 Ω
D. 5100 Ω

Question 5

Which of the following is true about an impulse voltage?

A. It is a unidirectional voltage
B. Chopped impulse flashover does not occur
C. Time taken to rise is equal to time taken to fall
D. RMS value is always less than 50% of average value

Question 6

Two resistors R1 = 36 Ω ± 5% and R2 = 75 Ω ± 5% are connected in series. The total resistance is

A. 111 ± 0 Ω
B. 111 ± 2.778 Ω
C. 111 ± 5.55 Ω
D. 111 ± 7.23 Ω

Question 7

It is required to measure angular position. Out of the transducers Circular potentiometerLVDTE pick upSynchro The proper devices are

A. 1, 2, 3, 4
B. 2 and 3
C. 1, 2, 4
D. 1 and 4

Question 8

Induction wattmeter can be used in

A. ac circuit only
B. dc circuit only
C. both ac and dc circuit
D. ac 3 phase only

Question 9

A moving coil instrument has a resistance of 0.6 Ω and full scale deflection at 0.1 A. To convert it into an ammeter of 0-15 A range, the resistance of shunt should be

A. 0.6 Ω
B. 0.06 Ω
C. 0.1 Ω
D. 0.004 Ω

Question 10

In which of the transformer is the secondary nearly short circuited under normal operating conditions?

A. CT
B. PT
C. Distribution transformer
D. Power transformer

Question 11

Loss of charge method is suitable for medium resistances.

A. TRUE
B. FALSE

Question 12

An ammeter of 0-25 A range has a guaranteed accuracy of 1% of full scale reading. The current measured is 5 A. The limiting error is

A. 2%
B. 2.50%
C. 4%
D. 5%

Question 13

The household energy meter is

A. indicating instrument
B. recording instrument
C. integrating instrument
D. none of the above

Question 14

A single phase energy meter has the rating 1200 resolutions/ kWh. If a 500 W electric gadget is used for 4 hours, the energy meter will make

A. 1200 revolutions
B. 1800 revolutions
C. 2100 revolutions
D. 2400 revolutions

Question 15

Which of the following statement is correct for two wattmeters method of power measurement in 3 phase circuit?

A. Power can be measured by this method only for star connected loads
B. When two wattmeters have equal readings power factor is 0.5.
C. When power factor is 1, one of the wattmeters readings is zero
D. When the two wattmeter read equal and opposite, p.f. is zero.

Question 16

The Lissajous pattern observed on screen of CRO is a straight line inclined at 45° to x axis. If X-plate input is 2 sin ωt, the Y-plate input is

A. 2 sin ωt
B. 2 sin (ωt + 45°)
C. 2 sin (ωt - 45°)
D. 22 sin ωt + 45°)

Question 17

In a strain measuring device using a strain gauge, the output quantity is

A. voltage
B. resistance
C. impedance
D. either (a) or (b)

Question 18

A dynamometer wattmeter is connected in ac circuit. The reading will be

A. V-A product
B. average power
C. peak power
D. instantaneous power

Question 19

In two wattmeter method of 3 phase power measurement, when does one wattmeter read negative

A. when power factor is less than 0.5 lagging
B. when power factor is greater than 0.5 lagging
C. when power factor is less than 0.5
D. when power factor is unity

Question 20

The coil of a moving iron instrument has a resistance of 500 Ω and an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If series resistance is 2000 Ω, its reading when fed by 250 V, 50 Hz ac will be

A. 260 V
B. 252 V
C. 250 V
D. 248 V

Question 21

A digital frequency counter can be converted to DVM by addition of a suitable

A. voltage controlled oscillator
B. D/A converter
C. power amplifier
D. operational amplifier

Question 22

The angle δ for a mica capacitor is about

A. 25°
B. 15°
C. 5°
D. 1°

Question 23

A moving coil instrument has a resistance of 0.5 Ω and a full scale deflection of 0.1 A. To convert it into an ammeter of 0-10 A the shunt resistance should be

A. 0.004 Ω
B. 0.005 Ω
C. 0.05 Ω
D. 0.1 Ω

Question 24

Consider the following statements: In a differential amplifier using JFET, the differential output offset is due to mismatch between FET parametersdifference in values of resistances used in circuitvariation in supply voltage. Of the statements, the correct statements are

A. 1 and 2
B. 1, 2, 3
C. 2, 3
D. 1, 3

Question 25

A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. The magnitude of unknown emf is

A. 1.39 V
B. 0.75 V
C. 13.9 V
D. 7.45 V

Question 26

Which of the following measurements using a dc potentiometer do not require standardisation of potentiometer?

A. Measurement of unknown voltage
B. Measurement of resistance
C. Measurement of unknown current
D. Calibration of voltmeter

Question 27

The coil of a moving coil meter has 100 turns, is 40 mm long and 30 mm wide. The control torque is 240 x 10-6 N-m on full scale. If B = 1 Wb/m2, range of meter is

A. 1 mA
B. 2 mA
C. 3 mA
D. 4 mA

Question 28

As per BIS there are 6 accuracy classes of instruments.

A. TRUE
B. FALSE

Question 29

Potentiometer method of dc voltage measurement is more accurate than direct measurement using a voltmeter because

A. it loads the circuit to maximum extent
B. it loads the circuit moderately
C. it does not load the circuit at all
D. it uses centre zero galvanometer instead of Voltmeters

Question 30

To increase Q factor of a coil, the wire should be

A. long
B. thin
C. thick
D. long and thin

Question 31

In 3 phase power measurement by two wattmeter method, the reading of one wattmeter is zero. The power factor of load is

A. 1
B. 0.5
C. 0
D. 0.8

Question 32

A piezoelectric force transducer has a charge sensitivity of 20 pC/N. It is connected to a charge amplifier and overall gain of transducer and amplifier is 50 mV/N. The gain of amplifier is

A. 1 mV/pC
B. 1.5 mV/pC
C. 2.5 mV/pC
D. 4 mV/pC

Question 33

A moving iron instrument gives correct reading when used at

A. low frequencies
B. high frequencies
C. only one frequency
D. all frequencies upto a certain value

Question 34

Which of the following are needed both for protection and metering?

A. Wattmeters
B. Instrument transformers
C. Energy meters
D. Power factor meters

Question 35

The speed transducer using a drag cup rotor has the main advantage of

A. very high accuracy
B. low energy requirement
C. cheap construction
D. all of the above

Question 36

Assertion (A): A hot wire ammeter has a cramped scale.Reason (R): The heat is proportional to square of current.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true

Question 37

A voltmeter using thermocouples measures

A. rms value
B. peak value
C. average value
D. peak to peak value

Question 38

In a ballistic galvanometer, a charge of 100 μC gives a first swing of 25°. The charge required to cause first swing of 50° is

A. 200 μC
B. 400 μC
C. 50 μC
D. 25 μC

Question 39

If reference sound pressure P0 is 2 x 10-5 N/m2, a sound pressure of 90 dB is equal to

A. 0.632 N/m2
B. 0.707 N/m2
C. 0.835 N/m2
D. 0.925 N/m2

Question 40

In a thermocouple temperature transducer, the output voltage is usually measured by

A. high resistance ammeter
B. high resistance voltmeter
C. high resistance milli-voltmeter
D. none of the above

Question 41

Magnetic flux density has the dimensions

A. MI-1T-2
B. M-1I-2T-2
C. ML-3T-2
D. MI-1T-3

Question 42

A dynamometer wattmeter is connected in ac circuit. The measured power is

A. rms power
B. average power
C. peak power
D. instantaneous power

Question 43

Assertion (A): De sauty's bridge is suitable only for pure capacitor.Reason (R): Capacitors are mostly perfect.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true

Question 44

In a CRO which of the following is not a part of electron gun

A. cathode
B. grid
C. accelerating anode
D. X - Y plates