Measuring Instruments MCQ Question Answer

1. In a megger when not in operation, the needle shows a resistance of

(a) Zero ohms
(b) Infinity
(c) 100 ohms
(d) 500 Ohms

2. A cadmium sulphide cell is a

(a) solar cell
(b) dry cell
(c) photo voltaic cell
(d) photo conductive cell.

3. A photo electric transducers are used for the measurement of any phenomenon which can be used to produce

(a) variation in current
(b) variation in voltage
(c) variation in light intensity
(d) variation in flux density.

4. A solar cell is

(a) same as a photometer
(b) same as a photo emissive cell
(c) same as a photo conductive cell
(d) same as a photo voltaic cell.

5. A load cell is a

(a) strain gauge
(b) photovoltaic cell
(c) thermistor
(d) pressure pickup.

6. Which of the following quantities cannot be measured by a load cell?

(a) pressure
(b) temperature
(c) level
(d) all of the above.

7. A cell in which a semiconductor having a negative illumination coefficient of resistance is used is known as

(a) triode
(b) photo-conductive cell
(c) photo voltaic cell
(d) photo meter.

8. Meggar will give resistance values which

(a) increase with the speed of the hand driven dynamo
(b) decrease with the speed of the hand driven dynamo
(c) remain constant irrespective of the speed
(d) any of the above.

9. For measuring an unknown electrical quantity, select the meter with

(a) highest range and work down
(b) lowest range and work up
(c) with middle range and work up and down on trial and error basis
(d) any of the above.

10. Moving iron meters are extensively used for the measurement of A.C. voltage and current because

(a) no current flows through the moving element and is robust
(b) its torque weight ratio is more
(c) it is very accurate.

11. Moving iron instruments are rarely used in low power high resistance circuits because of

(a) high resistance of the coil
(b) low reluctance of magnetic path
(c) high reluctance of magnetic path
(d) none of the above.

12. Scale of an instrument will be uniform if

(a) deflecting torque varies directly as the deflection angle
(b) control torque varies directly as the deflection angle
(c) deflecting torque varies directly as the deflection angle and control torque varies directly as the deflection angle
(d) damping torque varies directly as the deflection angle.

13. Which of the following instruments may be used to measure D.C. voltage accurately ?

(a) Moving iron type instrument
(b) Moving coil type instrument
(c) Electrodynamic type instrument
(d) None of the above.

14. A high resistance is usually connected in series with an electrostatic voltmeter

(a) for accuracy
(b) to increase the range
(c) for safety reasons
(d) none of the above.

15. In measuring instruments a mirror is provided behind the pointer with a purpose that

(a) with the help of the mirror it may be seen whether the pointer is bent or not
(b) the scale is illuminated through the mirror
(c) reading errors due to inclined observation are eliminated by removing parallax between the pointer and its image in the mirror
(d) any of the above.

16. The accuracy of a meter is determined by…………. deflection.

(a) one-tenth of full scale
(b) one-fourth of full scale
(c) half-scale
(d) full-scale.

17. The sensitivity inaccuracy of an instrument does not depend on

(a) frequency response
(b) hysteresis
(c) amplitude distortion
(d) all of the above.

18. The error, when reading at half-scale in an instrument, is

(a) equal to half of full-scale error
(b) equal to full-scale error
(c) less than full-scale error
(d) greater than full-scale error

19. An instrument’s reliability means

(a) extent to which the characteristics remain linear
(b) the life of the instrument
(c) the degree to which the repeatability continues to remain within specific limits
(d) all of the above.

20. Damping in an instrument provides

(a) counter torque to deflection torque
(b) good accuracy
(c) braking action on a meter pointer
(d) starting torque on the meter pointer.

21. In an instrument hysteresis means

(a) the inaccuracy due to change in temperature
(b) the reliability of the instrument
(c) the repeatability of the instrument
(d) the change in same reading when input is first increased and then decreased.

22. ………. meter has the best accuracy.

(a) Thermocouple
(b) Moving-coil
(c) Moving-iron
(d) Rectifier type

23. …………. damping method is common in moving coil instruments.

(a) Eddy current
(b) Fluid
(c) Spring
(d) Air

24. In an ammeter the shunt resistance is usually ……….. meter resistance.

(a) equal to
(b) less than
(c) greater than
(d) of any value.

25. A very accurate voltmeter, when used to measure voltage across a low resistance, gives inaccurate reading because

(a) the current drawn by the meter is too low
(b) the higher scale has been selected
(c) the sensitivity of the meter is too low
(d) any of the above
(e) none of the above.

26. Which of the following will happen if a voltmeter is connected like an ammeter in series to the load ?

(a) There will be almost no current in the circuit
(b) The measurement will be too high
(c) The meter will burn out
(d) A very high current will flow

27. The minimum number of wattmeters required to measure power in an unbalanced three-wire system is

(a) one
(b) two
(c) three
(d) four

28. The total power delivered to a three-phase load is equal to

(a) algebraic sum of two-wattmeter readings
(b) algebraic difference of two-watt meters readings
(c) vectorial sum of two-wattmeter readings
(d) vectorial difference of two-watt meters readings

29. An induction wattmeter measures

(a) only the true power
(b) the reactive power
(c) the apparent power
(d) the true power and the reactive power.

30. The Q-meter Works on the principle of

(a) self-inductance
(b) mutual inductance
(c) series resonant circuit
(d) parallel resonant circuit

31. Which of the following properties are measured by a Q-meter ?

(a) Electrical properties of the coils only
(b) Mechanical properties of the coils only
(c) Electrical properties of capacitors only
(d) Electrical properties of both the coils and capacitors.

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