# Measurements and Instrumentation Part Two

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

1. The
power input and output in a device are 3650 W and 3385 W with each
reading in doubt by ± 10 W. The percentage uncertainty in losses is

1. ± 7.55%
2. ± 3.77%
3. ± 15.09%
4. ± 11.32%

2. A
meter coil has a resistance of 100 Ω and a full scale deflection
current of 10 mA. To convert it into a voltmeter of 0-200 V range, the
series resistance should be

1. 1.9 kΩ
2. 20.1 kΩ
3. 20 kΩ
4. 19.9 kΩ

3. Which of these has a magnetic brake?
1. Dynamometer wattmeter
2. Energy meter
3. Thermocouple ammeter
4. Frequency meter

4. Two numbers are 131 ± 5 and 629 ± 3. The sum of the numbers with range of doubt is
1. 760 + 8
2. 760 ± 2
3. 760 – 8
4. 760 ± 8

5. Assertion
(A): Schering bridge is a low voltage bridge. Reason (R): Schering
bridge is very commonly used for measurement of capacitance.

1. Both A and R are true and R is 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 but R is not correct explanation of A

6. Assertion
(A): Wien bridge can be used for measuring frequency.Reason (R): A
frequency meter for 50 Hz system has a frequency range of 40 to 60 Hz.

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

7. Which of these has poor overload capacity?
1. Dynamometer instrument
2. all of rhese
3. Hot wire instrument
4. PMMC instrument

8. In 3 phase power measurement by two wattmeter method, both wattmeters had equal reading. The power factor of load is
1. 0.5 lagging
2. 1
4. 0

9. Which instrument is based on induction principle?
1. Dynamometer wattmeter
2. Energy meter
3. Induction wattmeter
4. Induction wattmeter and Energy meter

10. Magnetic field intensity has the dimensions
1. none of these
2. IL
3. IL⁻¹
4. I²L

11. The volt ratio box is basically a
1. all of these
2. current transformer
3. potential divider
4. a high resistance voltmeter

12. A
sinusoidal ac voltage of amplitude 100 V is applied to a rectifying
device which offers 10 Ω resistance in forward direction and infinite
resistance in backward direction. A moving coil ammeter is also
connected in the circuit. The reading of ammeter will be

1. 10 A
2. 14.14 A
3. 3.185 A
4. 5 A

13. A
variable reluctance tachometer has 180 teeth on rotor. The speed of
shaft on which it is mounted in 1200 rpm. The frequency of output pulses
is

1. 3600 per second
2. 5600 per second
3. 1800 per second
4. 4800 per second

14. Consider
the following operation in respect of Wheatstone bridge (Kb, denotes
battery key, Kg denotes galvanometer key)1.open Kb 2.close Kg3. close Kb
4.open Kg The correct sequence of operations is

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

15. Two
voltmeters 0-250 V each having resistances of 5 kΩ and 10 kΩ
respectively and are connected in series. To ensure that neither of them
goes beyond scale the total voltage which can be applied should be less
than

1. 400 V
2. 500 V
3. 375 V
4. 250 V

16. A
24 mm long conductor has a resistance of 128 Ω. The change in
resistance is 13.3 Ω and change in length is 1.6 mm under tension. The
gauge factor is

1. 1.2
2. 2.1
3. 2.6
4. 1.6

17. Measuring of unknown voltage with a dc potentiometer loses its advantage of open circuit measurement when
1. range reduction by factor of 10 is employed
2. voltage is larger than range of potentiometer
3. standardisation is done to compensate for drift
4. primary circuit battery is changed

18. In
a digital measuring device the input electrical signal is in the
frequency range of dc to ac (50) Hz. It must be sampled at a rate of

1. f times/sec
2. 0.5 f times/sec
3. 0.25 f times/sec
4. 2 f times/sec

19. A meter has a square law scale. For 2 A current the deflection in 90°. For a deflection of 45°, the current is
1. 1 A
2. 1.5 A
3. 1.414 A
4. 1.61 A

20. Consider
the following Statements regarding resistance strain gauge 1.The gauge
factor is in the range of 2 to 5, 2.The resistance changes due to change
in specific resistance with strain, 3.The resistance increases with
increase in temperature. Of the above statements, which are correct?

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

21. A
sinusoidal ac voltage of amplitude 100 V is applied to a rectifying
device which offers 10 Ω resistance in forward direction and infinite
resistance in reverse direction. The reading on hot wire ammeter will be

1. 3.185 A
2. 5 A
3. 10 A
4. 1.414 A

22. When
a capacitor is connected to the terminals of an ohmmeter, the pointer
indicated a low resistance initially and finally come to infinity
position. This shows that capacitor is

1. faulty
2. open circuited
3. all right
4. short circuited

23. If eddy current damping is to be used, the disc of instrument should be
1. conducting and magnetic
2. non-conducting and non-magnetic
3. conducting and non-magnetic
4. non-conducting and magnetic

24. The scale of moving iron instrument is linear.
1. True
2. False

25. With a variable reluctance tachometer having 60 rotor teeth the count reads 3600 counts per minute. The speed in RPM is
1. 60
2. 3600
3. 36
4. 360

26. When measuring phase angle between two waves using a CRO, the time base generator is connected to
1. Y plate
2. neither X nor Y plates
3. both X and Y plate
4. X plate

27. It is required that a strain gauge has gauge factor of 100. The proper strain gauge is
1. alloy strain gauge
2. constantan strain gauge
3. nichrome strain gauge
4. semiconductor strain gauge

28. A
meter having 0-1000 μA range and 1000 Ω resistance is required to be
changed to 0-100 mA meter. The value of shunt resistance is about

1. 100 Ω
2. 99 Ω
3. 10 Ω
4. 1 Ω

29. An induction wattmeter can be used for
1. dc only
2. 50 Hz ac only
3. high frequency ac only
4. both ac and dc

30. If the current in a capacitor leads the voltage by 80°, the loss angle of capacitor is
1. 10°
2. 80°
3. 170°
4. 100°

31. In an induction wattmeter, the shading bands are made of non conducting material.
1. True
2. False

32. The current in a circuit is measured using a 150 : 1 CT If the ammeter reads 0.6 A, the circuit current is
1. 250 A
2. 90 A
3. 156 A
4. 144 A

33. A volt ratio box should have low resistance.
1. True
2. False

34. A Hall effect transducer has KH = – 1 x 10⁻⁸. If B = 1 Wb/m², I = 3 A and bismuth slab is 2 mm wide, the Hall voltage is
1. -22.5 x 10⁻⁴ V
2. -15 x 10⁻⁶ V
3. -20 x 10⁻⁴
4. -7.5 x 10⁻⁶ V

35. Two
ammeters A and B both 0-10 A have internal resistance of 1 Ω and 0.5 Ω
respectively. They are connected in parallel. If total current is 15 A,
then

1. IA = 10 A, IB = 5 A
2. IA = 5 A, IB = 10 A
3. IA = 9 A, IB = 6 A
4. IA = IB = 7.5 A

36. Which of the following is not correct?
1. An ammeter should have a very low resistance
2. Voltmeter should have a very high resistance
3. A shunt should have a very low resistance
4. An electronic voltmeter draws appreciable current from source

37. The loss of charge method can be used to measure
1. resistance of shunt
2. resistance of shunt winding
3. all of these
4. insulation resistance of cable

38. Assertion
(A): Maxwell bridge is for measuring inductance of medium magnitude.
Reason (R): In Maxwell’s bridge the unknown inductance is measured by
comparing it with a capacitance.

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

39. Assertion
(A): A semiconductor strain gauge is more accurate than a resistance
strain gauge.Reason (R): The gauge factor of a semiconductor strain
gauge is about 100 where as the gauge factor of a resistance strain
gauge is only about 2.

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

40. Current density has the dimensions
1. IL⁻²
2. L²I
3. I⁻²L²
4. IL

41. The
resistance of a dc galvanometer is 20 Ω. A current of 10 mA causes full
scale deflection. To convert it into 0-300 V voltmeter, we have to use a
series resistance of

1. 6000 Ω
2. 30000 Ω
3. 15 Ω
4. 29980 Ω

42. A capacitance transducer can be used to measure
1. displacement
2. level of fluids
3. All of these
4. thickness of sheet

43. The dynamometer principle can be used for
1. wattmeter only
2. ammeter, voltmeter and wattmeter
3. voltmeter only
4. ammeter only

44. Assertion
(A): In hot wire instrument the material of hot wire in generally
platinum iridium.Reason (R): A hot wire ammeter is suitable for ac only

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

45. The scale of hot wire ammeter is
1. linear
2. non-linear
3. absolute linear
4. cramped

46. A
moving coil meter has a shunt of 0.02 Ω resistance. If coil resistance
is 1000 Ω and a potential difference of 500 mV is required across it to
cause full scale deflection, the current through shunt is

1. 0.025 A
2. 0.25 A
3. 2.5 A
4. 25 A

47. Consider
the following features of an instrument 1.suitable for both ac and
dc,2.free from hysteresis and eddy current errors,3.No waveform and
frequency errors,4.it is essentially a voltmeter.This instrument is

1. moving coil
2. dynamometer
3. moving iron
4. electrostatic

48. Which one of the following effects is used in measuring power?
1. Induction
2. Ferrari
3. Seeback
4. Hall

49. The effect of lead resistance is important in measurement of
1. resistance of ammeter
2. resistance of shunt winding
3. resistance of shunt
4. resistance of shunt and resistance of ammeter

50. A
resistance wire strain gauge has gauge factor 2. If stress is 100 mega
newton/m² and Young’s modulus is 200 giga newton/ m², the percentage
change in gauge resistance due to stress is

1. 0.1
2. 0.
3. 0.3
4. 0.2