Prepare effectively for competitive exams like SSC JE, RRB JE, UPPCL JE, and other Electrical Engineering exams with these well-curated multiple-choice questions on Electrical Measurements. Each question comes with the correct answer to help you test and enhance your knowledge.
1. In a moving iron instrument, the deflection is proportional to:
A. Current (I)
B. Voltage (V)
C. Power (P)
D. Square of the current (I²)
✅ Answer: D. Square of the current (I²)
2. A 230 V, single-phase energy meter has a constant load of 4 A passing through it for 6 hours at unity power factor. The meter disc makes 2208 revolutions during this period. What will be the energy consumed by the load if the meter disc completes 1240 revolutions?
A. 2.5 kWh
B. 2.8 kWh
C. 3.5 kWh
D. 3.1 kWh
✅ Answer: D. 3.1 kWh
3. The power factor of an RLC circuit is 0.8 lagging. What is the phase angle between voltage and current?
A. 36.87°
B. 45°
C. 53.13°
D. 60°
✅ Answer: A. 36.87°
4. Which instrument is used for measuring high resistance?
A. Megger
B. Wattmeter
C. Ammeter
D. Voltmeter
✅ Answer: A. Megger
5. In a CRO, the horizontal deflection is controlled by:
A. Vertical amplifier
B. Time base generator
C. Delay line
D. Trigger circuit
✅ Answer: B. Time base generator
6. The deflection in a PMMC instrument is proportional to:
A. Current
B. Voltage
C. Power
D. Frequency
✅ Answer: A. Current
7. A dynamometer type wattmeter can measure:
A. DC power only
B. AC power only
C. Both AC and DC power
D. Reactive power
✅ Answer: C. Both AC and DC power
8. The range of a voltmeter can be extended by using:
A. Shunt resistor
B. Series resistor
C. Transformer
D. Capacitor
✅ Answer: B. Series resistor
9. The sensitivity of a voltmeter is defined as:
A. Current per volt
B. Voltage per ampere
C. Ohms per volt
D. Volts per ohm
✅ Answer: C. Ohms per volt
10. Which instrument is most suitable for measuring alternating current?
A. PMMC instrument
B. Moving iron instrument
C. Electrodynamometer
D. Thermocouple instrument
✅ Answer: B. Moving iron instrument
11. In a 3-phase energy meter, the number of revolutions made by the disc in a given time is proportional to:
A. Voltage
B. Current
C. Power
D. Energy consumed
✅ Answer: D. Energy consumed
12. The main function of a current transformer is to:
A. Step up the voltage
B. Step down the voltage
C. Step up the current
D. Step down the current
✅ Answer: D. Step down the current
13. The damping torque in a measuring instrument is provided to:
A. Increase the speed of response
B. Reduce the oscillations
C. Increase the sensitivity
D. Reduce the friction
✅ Answer: B. Reduce the oscillations
14. In a digital voltmeter, the analog input is converted to digital using:
A. ADC
B. DAC
C. Counter
D. Flip-flop
✅ Answer: A. ADC
15. The instrument suitable for measuring transient currents is:
A. Moving coil instrument
B. Moving iron instrument
C. Cathode ray oscilloscope (CRO)
D. Electrodynamometer
✅ Answer: C. Cathode ray oscilloscope
16. The accuracy of an instrument is defined as:
A. Closeness to the true value
B. Repeatability of the readings
C. Smallest change it can detect
D. Time taken to respond
✅ Answer: A. Closeness to the true value
17. Which instrument is used to measure both AC and DC current?
A. Thermocouple instrument
B. Electrodynamometer
C. Moving iron instrument
D. PMMC instrument
✅ Answer: C. Moving iron instrument
18. Which part of a measuring instrument ensures that the pointer comes to rest at the correct position without oscillation?
A. Controlling torque
B. Restoring spring
C. Moving system
D. Damping torque
✅ Answer: D. Damping torque
19. Which instrument is most suitable for laboratory measurement of high AC voltage?
A. PMMC instrument
B. Electrodynamometer
C. Electrostatic voltmeter
D. Moving iron instrument
✅ Answer: C. Electrostatic voltmeter
20. Which instrument has the highest torque-to-weight ratio?
A. Moving iron instrument
B. PMMC instrument
C. Electrodynamometer
D. Hot wire instrument
✅ Answer: B. PMMC instrument