# Measurements and Instrumentation Part One

1. To increase Q factor of a coil, the wire should be
1. long and thin
2. thin
3. long
4. thick

2. 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

1. 2.5%
2. 5%
3. 4%
4. 2%

3. In 3 phase power measurement by two wattmeter method, the reading of one wattmeter is zero. The power factor of load is
1. 0.5
2. 0.8
3. 0
4. 1

4. In a CRO which of the following is not a part of electron gun
1. accelerating anode
2. X – Y plates
3. cathode
4. grid

5. Which of the following voltmeters would you use for measuring voltage across 20 kΩ resistance?
1. Voltmeter having sensitivity of 10 kW/V
2. Voltmeter having a sensitivity of 1 kW/V
3. None of these
4. Voltmeter having a resistance of 5 kΩ

6. 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

1. 2400 revolutions
2. 2100 revolutions
3. 1200 revolutions
4. 1800 revolutions

7. Assertion (A): De sauty’s bridge is suitable only for pure capacitor. Reason (R): Capacitors are mostly perfect.
1. A is false R is true
2. A is true R is false
3. Both A and R are true but R is not correct explanation of A
4. Both A and R are true and R is correct explanation of A

8. In which of the transformer is the secondary nearly short circuited under normal operating conditions?
1. Distribution transformer
2. Power transformer
3. PT
4. CT

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

1. 0.6 Ω
2. 0.004 Ω
3. 0.1 Ω
4. 0.06 Ω

10. 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

1. 2.5 mV/pC
2. 4 mV/pC
3. 1 mV/pC
4. 1.5 mV/pC

11. 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

1. 0.5 V/mm
2. 5 V/mm
3. 1 V/mm
4. 0.1 V/mm

12. Assertion
(A): When a wattmeter is used for low impedance loads, the pressure
coil is connected across the load. Reason (R): A wattmeter measures
apparent power.

1. A is true R is false
2. A is false R is true
3. Both A and R are true but R is not correct explanation of A
4. Both A and R are true and R is correct explanation of A

13. As per BIS there are how many accuracy classes of instruments.
1. 2
2. 6
3. 8
4. 5

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

1. 400 μC
2. 50 μC
3. 200 μC
4. 25 μC

15. Two resistors R1 = 36 Ω plus,minus 5% and R2 = 75 Ω plus,minus 5% are connected in series. The total resistance is
1. 111 plus,minus 7.23 Ω
2. 111 plus,minus 5.55 Ω
3. 111 plus,minus 2.778 Ω
4. 111 plus,minus 0 Ω

16. In a strain measuring device using a strain gauge, the output quantity is
1. resistance
2. impedance
3. voltage
4. all of these

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

1. 2 sin ωt
2. 2 sin (ωt – 45)
3. 2√2 sin ωt + 45)
4. 2 sin (ωt + 45)

18. The angle δ for a mica capacitor is about
1. 5
2. 1
3. 15
4. 25

19. 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
1. 0.01 V
2. 1 V
3. 1 mV
4. 1 μV

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

1. 2 mA
2. 3 mA
3. 1 mA
4. 4 mA

21. Consider
the following statements: In a differential amplifier using JFET, the
differential output offset is due to-1.mismatch between FET
parameters,2.difference in values of resistances used in
circuit,3.variation in supply voltage.Of the statements, the correct
statements are

1. 1, 3
2. 2, 3
3. 1, 2, 3
4. 1 and 2

22. 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

1. 4900 Ω
2. 5100 Ω
3. 490 Ω
4. 5000 Ω

23. The household energy meter is
1. integrating instrument
2. none of these
3. indicating instrument
4. recording instrument

24. 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

1. 13.9 V
2. 0.75 V
3. 1.39 V
4. 7.45 V

25. 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

1. 0.1 Ω
2. 0.005 Ω
3. 0.004 Ω
4. 0.05 Ω

26. Potentiometer method of dc voltage measurement is more accurate than direct measurement using a voltmeter because
1. it uses centre zero galvanometer instead of Voltmeters
2. it does not load the circuit at all
3. it loads the circuit moderately
4. it loads the circuit to maximum extent

27. Assertion (A): A hot wire ammeter has a cramped scale.Reason (R): The heat is proportional to square of current.
1. Both A and R are true but R is not correct explanation of A
2. A is true R is false
3. A is false R is true
4. Both A and R are true and R is correct explanation of A

28. Which of the following is true about an impulse voltage?
1. It is a unidirectional voltage
2. RMS value is always less than 50% of average value
3. Chopped impulse flash over does not occur
4. Time taken to rise is equal to time taken to fall

29. Which of the following are needed both for protection and metering?
1. Power factor meters
2. Wattmeters
3. Energy meters
4. Instrument transformers

30. A digital frequency counter can be converted to DVM by addition of a suitable
1. operational amplifier
2. power amplifier
3. D/A converter
4. voltage controlled oscillator

31. A dynamometer wattmeter is connected in ac circuit. The reading will be
1. V-A product
2. average power
3. instantaneous power
4. peak power

32. The speed transducer using a drag cup rotor has the main advantage of
1. all of these
2. cheap construction
3. very high accuracy
4. low energy requirement

33. A voltmeter using thermocouples measures
1. average value
2. peak value
3. peak to peak value
4. rms value

34. Which of the following measurements using a dc potentiometer do not require standardization of potentiometer?
1. Measurement of unknown voltage
2. Calibration of voltmeter
3. Measurement of resistance
4. Measurement of unknown current

35. Which of the following statement is correct for two wattmeters method of power measurement in 3 phase circuit?
1. Power can be measured by this method only for star connected loads
2. When two wattmeters have equal readings power factor is 0.5.
3. When power factor is 1, one of the wattmeters readings is zero
4. When the two wattmeter read equal and opposite, p.f. is zero

36. A moving iron instrument gives correct reading when used at
1. low frequencies
2. only one frequency
3. all frequencies upto a certain value
4. high frequencies

37. Induction wattmeter can be used in
1. ac 3 phase only
2. ac circuit only
3. dc circuit only
4. both ac and dc circuit

38. A dynamometer wattmeter is connected in ac circuit. The measured power is
1. instantaneous power
2. rms power
3. average power
4. peak power

39. Loss of charge method is suitable for
1. high resistances.
2. all of these.
3. medium resistances.
4. low resistances.

40. In two wattmeter method of 3 phase power measurement, when does one wattmeter read negative
1. when power factor is less than 0.5 lagging
2. when power factor is unity
3. when power factor is less than 0.5
4. when power factor is greater than 0.5 lagging

41. It
is required to measure angular position. Out of the
transducers-1.Circular potentiometer,2.LVDT,3.E pick up,4.Synchro.The
proper devices are

1. 1 and 4
2. 1, 2, 3, 4
3. 2 and 3
4. 1, 2, 4

42. Kelvin’s double bridge is used to measure low resistances because
1. effect of contact and lead resistances is eliminated
2. there is no thermoelectric emf
3. resistance variation due to temperature
4. it has high sensitivity

43. Assertion (A): Shunt of an ammeter has a low resistance.Reason (R): Shunt may be connected in series or in parallel with ammeter
1. Both A and R are true but R is not correct explanation of A
2. Both A and R are true and R is correct explanation of A
3. A is true R is false
4. A is false R is true

44. The scale of hot wire instrument is
1. both
2. non linear.
3. none
4. linear.

45. The resistance of a 125 Ω strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is
1. 2.5
2. 1
3. 2
4. 1.5

46. If an inductance L is connected in one arm of bridge and resistance R1, R2, R3 in other three arms
1. the bridge is balanced for some specific values of R1, R2, R3
2. the bridge cannot be balanced
3. the bridge can be balanced
4. the bridge is balanced for some specified value of frequency

47. LVDT is a
1. velocity transducer
2. acceleration transducer
3. pressure transducer
4. displacement transducer

48. A 0-200 V voltmeter has an accuracy of 0.75% of full scale reading. If voltage measured is 100 V, the error is
1. 2%
2. 3%
3. 1.5%
4. 75%

49. In Schering bridge, the potential of detector above earth potential is about
1. 10 KV
2. 1000 V
3. a few volts
4. none of these

50. Which
of the following instruments has non-linear scale? 1.Moving coil
instrument,2.Moving iron instrument,3.Electrostatic
instrument,4.Rectifier instrument.Select the answer as per following
codes

1. 2 and 3 only
2. 2, 3 and 1
3. 1, 2, 3 and 4
4. 2 only