Measurements and Instrumentation Part 1 ONLINE MCQ EE AND ECE

Measurements and Instrumentation Part 1

Measurements and Instrumentation Part One

Instructions: Click the answer button to see the correct answer.

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

1. long and thin
2. thin
3. long
4. thick

Answer: d

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%

Answer: b

Measurements and Instrumentation Part 1

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

Answer: a

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

Answer: b

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

Answer: a

Measurements and Instrumentation Part 1

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

Answer: a

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

Answer: b

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

Answer: d

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

Answer: b

Measurements and Instrumentation Part 1

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

Answer: a

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

Answer: c

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

Answer: a

Measurements and Instrumentation Part 1

13. As per BIS there are how many accuracy classes of instruments.

1. 2
2. 6
3. 8
4. 5

Answer: c

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

Answer: c

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

Answer: b

Measurements and Instrumentation Part 1

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

1. resistance
2. impedance
3. voltage
4. all of these

Answer: c

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)

Answer: a

18. The angle δ for a mica capacitor is about

1. 5
2. 1
3. 15
4. 25

Answer: b

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

Answer: c

Measurements and Instrumentation Part 1

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

Answer: a

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

Answer: d

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

Answer: a

Measurements and Instrumentation Part 1

23. The household energy meter is

1. integrating instrument
2. none of these
3. indicating instrument
4. recording instrument

Answer: a

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

Answer: c

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

Answer: b

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

Answer: b

Measurements and Instrumentation Part 1

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

Answer: d

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

Answer: a

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

1. Power factor meters
2. Wattmeters
3. Energy meters
4. Instrument transformers

Answer: d

Measurements and Instrumentation Part 1

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

Answer: c

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

Answer: b

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

Answer: d

33. A voltmeter using thermocouples measures

1. average value
2. peak value
3. peak to peak value
4. rms value

Answer: d

Measurements and Instrumentation Part 1

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

Answer: c

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

Answer: d

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

Answer: b

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

Answer: b

Measurements and Instrumentation Part 1

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

Answer: c

39. Loss of charge method is suitable for

1. high resistances.
2. all of these.
3. medium resistances.
4. low resistances.

Answer: a

Measurements and Instrumentation Part 1

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

Answer c

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

Answer: a

Measurements and Instrumentation Part 1

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

Answer: a

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

Answer: c

44. The scale of hot wire instrument is

1. both
2. non linear.
3. none
4. linear.

Answer: b

Measurements and Instrumentation Part 1

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

Answer: c

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

Answer: b

47. LVDT is a

1. velocity transducer
2. acceleration transducer
3. pressure transducer
4. displacement transducer

Answer: d

Measurements and Instrumentation Part 1

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%

Answer: c

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

Answer: c

Measurements and Instrumentation Part 1

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

Answer: a