MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Measurements knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Two watt-meters connected to measure the total power on a three-phase system supplying a balanced load reads 10.5 kW and -2.5 kW respectively. Then the total power factor is? |
| A. | 0.334 |
| B. | 0.684 |
| C. | 0.52 |
| D. | 0.334 |
| Answer» E. | |
| 2. |
In the Two wattmeter method of measuring power in a balanced three-phase circuit, one wattmeter shows zero and the other positive maximum. The load power factor is? |
| A. | 0 |
| B. | 0.5 |
| C. | 0.866 |
| D. | 1.0 |
| Answer» C. 0.866 | |
| 3. |
An average-reading digital Multimeter reads 10 V when fed with a triangular wave, symmetric about the time-axis. If the input is same, the rms reading meter will read? |
| A. | 20/ ( sqrt{3} ) |
| B. | -10/ ( sqrt{3} ) |
| C. | -20/ ( sqrt{3} ) |
| D. | 10/ ( sqrt{3} ) |
| Answer» E. | |
| 4. |
A 3-phase, 600 V motor, the load having 0.6 power factor uses two watt-meter to measure the power. If the power measured be 45 kW, then the reading of each instrument will be? |
| A. | P<sub>1</sub> = 35 kW, P<sub>2</sub> = 10 kW |
| B. | P<sub>1</sub> = 47.25 kW, P<sub>2</sub> = -2.25 kW |
| C. | P<sub>1</sub> = 39.82 kW, P<sub>2</sub> = 5.179 kW |
| D. | P<sub>1</sub> = 45 kW, P<sub>2</sub> = 0 kW |
| Answer» D. P<sub>1</sub> = 45 kW, P<sub>2</sub> = 0 kW | |
| 5. |
The meter constant of a single-phase, 100 V induction watt-meter is 600 rev/kW-h. The speed of the meter disc for a current of 15 A at 0.8 power factor lagging will be? |
| A. | 30.3 rpm |
| B. | 16 rpm |
| C. | 12 rpm |
| D. | 33.1 rpm |
| Answer» D. 33.1 rpm | |
| 6. |
The line to line input voltage to the 3-phase, 50 Hz, AC circuit, is 100 V rms. Assuming that the phase sequence is RYB; the watt-meters would read? |
| A. | W<sub>1</sub> = 886 W and W<sub>2</sub> = 886 W |
| B. | W<sub>1</sub> = 500 W and W<sub>2</sub> = 500 W |
| C. | W<sub>1</sub> = 0 W and W<sub>2</sub> = 1000 W |
| D. | W<sub>1</sub> = 250 W and W<sub>2</sub> = 750 W |
| Answer» D. W<sub>1</sub> = 250 W and W<sub>2</sub> = 750 W | |
| 7. |
A sampling watt-meter is used to measure the average power of a load. The peak to peak voltage of the square wave is 10 V and the current is a triangular wave of 5A p-p. The reading in watt will be? |
| A. | Zero |
| B. | 25 W |
| C. | 50 W |
| D. | 100 W |
| Answer» B. 25 W | |
| 8. |
A circuit is used to measure the power consumed by the load. The current coil and the voltage coil of the watt-meter have 0.02 and 1000 resistances respectively. The measured power (as compared to the load power) will be? |
| A. | 0.4 % less |
| B. | 0.2 % less |
| C. | 0.2 % more |
| D. | 0.4 % more |
| Answer» D. 0.4 % more | |
| 9. |
Two watt-meters, which are connected to measure the total power on a three-phase system supplying a balanced load, read 20.5 kW and -3.5 kW respectively. The total power is? |
| A. | 13.0 kW |
| B. | 17 kW |
| C. | 15 kW |
| D. | 19 kW |
| Answer» E. | |
| 10. |
A coil (which can be modelled as a series RL circuit) has been designed for high Q performance. The voltage is rated at and a specified frequency. If the frequency of operation is increased 10 times and the coil is operated at the same rated voltage. The new value of Q factor and the active power P will be? |
| A. | P is doubled and Q is halved |
| B. | P is halved and Q is doubled |
| C. | P remains constant and Q is doubled |
| D. | P decreases 100 times and Q is increased 10 times |
| Answer» E. | |