Basic Electrical Engineering Questions and Answers – Average and RMS Values of an Alternating Current

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This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Average and RMS Values of an Alternating Current”.

1. Find the average value of current when the current that are equidistant are 4A, 5A and 6A.
a) 5A
b) 6A
c) 15A
d) 10A
View Answer

Answer: a
Explanation: The average value of current is the sum of all the currents divided by the number of currents. Therefore average current = (5+4+6)/3=5A.
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2. What is the current found by finding the current in an equidistant region and dividing by n?
a) RMS current
b) Average current
c) Instantaneous current
d) Total current
View Answer

Answer: b
Explanation: The average value of the current is the sum of all the currents divided by the number of currents.

3. RMS stands for ________
a) Root Mean Square
b) Root Mean Sum
c) Root Maximum sum
d) Root Minimum Sum
View Answer

Answer: a
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.
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4. 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

Answer: a
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.

5. __________ current is found by dividing the area enclosed by the half cycle by the length of the base of the half cycle.
a) RMS current
b) Average current
c) Instantaneous current
d) Total current
View Answer

Answer: b
Explanation: The average value of current is the sum of all the currents divided by the number of currents. Hence it can also be found by dividing the area enclosed by the half cycle by the length of the base of the half cycle.
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6. What is the effective value of current?
a) RMS current
b) Average current
c) Instantaneous current
d) Total current
View Answer

Answer: a
Explanation: RMS current is also known as the effective current. 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.

7. In a sinusoidal wave, average current is always _______ rms current.
a) Greater than
b) Less than
c) Equal to
d) Not related
View Answer

Answer: b
Explanation: The average value of current is the sum of all the currents divided by the number of currents whereas RMS current is obtained by squaring all the current values, finding the average and then finding the square root. Hence RMS current is greater than average current.
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8. For a rectangular wave, average current is ______ rms current.
a) Greater than
b) Less than
c) Equal to
d) Not related
View Answer

Answer: c
Explanation: The rms value is always greater than the average except for a rectangular wave, in which the heating effect remains constant so that the average and the rms values are the same.

9. Peak value divided by the rms value gives us?
a) Peak factor
b) Crest factor
c) Both peak and crest factor
d) Neither peak nor crest factor
View Answer

Answer: c
Explanation: Peak and crest factor both mean the same thing. Hence the peak value divided by the rms value gives us the peak or crest factor.
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10. Calculate the crest factor if the peak value of current is 10A and the rms value is 2A.
a) 5
b) 10
c) 5A
d) 10A
View Answer

Answer: a
Explanation: We know that:
Crest factor = Peak value/RMS value.
Substituting the values from the given question, we get crest factor=5.

Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.

To practice all areas of Basic Electrical Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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