This set of Basic Electrical Engineering Questions and Answers for Aptitude test focuses on “Phasor Diagrams Drawn with r.m.s. Values Instead of Maximum Values”.

1. Ammeters and voltmeters are calibrated to read?

a) RMS value

b) Peak value

c) Average value

d) Instantaneous value

View Answer

Explanation: Ammeters and voltmeters are calibrated to read the rms value because the rms value is the most accurate average value.

2. The rms value is _________ times he maximum value

a) 1.414

b) 0.5

c) 2

d) 0.707

View Answer

Explanation: We know that the rms value is i/root(2) time the maximum value, hence the rms vale is 0.707 times the maximum value.

3. The rms value is 0.707 times the _________ value.

a) Peak

b) Instantaneous

c) Average

d) DC

View Answer

Explanation: We know that the rms value is i/root(2) time the peak value, hence the rms vale is 0.707 times the peak value.

4. If the phasors are drawn to represent the rms values, instead of the maximum values, what would happen to the phase angle between quantities?

a) Increases

b) Decreases

c) Remains constant

d) Becomes zero

View Answer

Explanation: When phasors are drawn representing the rms values instead of the maximum value, the shape of the diagram remains unaltered and hence the phase angle remains the same.

5. Usually phasor diagrams are drawn representing?

a) RMS value

b) Peak value

c) Average value

d) Instantaneous value

View Answer

Explanation: Ammeters and voltmeters are calibrated to read the rms value, hence the phasors are drawn representing the rms values.

6. A phasor has frozen at 30 degrees, find the value of the phase angle?

a) 30 degrees

b) 60 degrees

c) 120 degrees

d) 180 degrees

View Answer

Explanation: The value of the phase angle is the value at which the phasor stops or freezes. Here, it freezes at 30 degree, hence the phase angle is 30 degrees.

7. The time axis of an AC phasor represents?

a) Time

b) Phase angle

c) Voltage

d) Current

View Answer

Explanation: The time axis while measuring an AC sinusoidal voltage or current represents the phase angle when converting it to a phasor.

8. The length of the phasor represents?

a) Magnitude of the quantity

b) Direction of the quantity

c) Neither magnitude nor direction

d) Either magnitude or direction

View Answer

Explanation: The length of the phasor arrow represents the magnitude of the quantity, whereas the angle between the phasor and the reference represents the phase angle.

9. What is the type of current obtained by finding the square of the currents and then finding their average and then fining the square root?

a) RMS current

b) Average current

c) Instantaneous current

d) Total current

View Answer

Explanation: RMS stands for Root Mean Square. This value of current is obtained by squaring all the current values, finding the average and then finding the square root.

10. For a direct current, the rms current is ________ the mean current.

a) Greater than

b) Less than

c) Equal to

d) Not related to

View Answer

Explanation: For a direct current, that is, a non-sinusoidal current, the mean current value is same as that of the rms current.

**Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.**

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