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Electrical Instruments MCQ Questions & Answers

Electrical Instruments MCQs : This section focuses on the "Electrical Instruments". These Multiple Choice Questions (MCQs) should be practiced to improve the Electrical Instruments skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

A 0-400V voltmeter has a guaranteed accuracy of 1% of full scale reading. The voltage measured by this instrument is 250 V. Calculate the limiting error in percentage.

A. 4%
B. 2%
C. 2.5%
D. 1%

View Answer

Question 2

A 500 A, 50 Hz current transformer has a bar primary. The secondary burden is a pure resistance of 1 ? and it draws a current of 5 A. If the magnetic core requires 250 Ampere-turn for magnetization, the percentage ratio error is __________

A. 10.56%
B. -10.56%
C. 11.80%
D. -11.80%

View Answer

Question 3

A resistor of 10 k? with the tolerance of 5% is connected in parallel with 5 k? resistors of 10% tolerance. What is the tolerance limit for a parallel network?

A. 9%
B. 12.4%
C. 8.33%
D. 7.87%

View Answer

Question 4

A resistor of 10 k? with the tolerance of 5% is connected in series with 5 k? resistors of 10% tolerance. What is the tolerance limit for a series network?

A. 9%
B. 12.04%
C. 8.67%
D. 6.67%

View Answer

Question 5

A voltmeter has a sensitivity of 1000 ?/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The actual resistance of the unknown resistor will be?

A. 20 k?
B. 18.57 k?
C. 21.43 k?
D. 22.76 k?

View Answer

Question 6

A voltmeter has a sensitivity of 1000 ?/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The apparent resistance of the unknown resistor will be?

A. 20 k?
B. 21.43 k?
C. 18.57 k?
D. 22.36 k?

View Answer

Question 7

A voltmeter has a sensitivity of 1000 ?/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The error due to the loading effect of the voltmeter is ________

A. 3.33%
B. 6.67%
C. 13.34%
D. 13.67%

View Answer

Question 8

Resistances R1 and R2 have respectively, nominal values of 10? and 5? and limiting error of ± 5% and ± 10%. The percentage limiting error for the series combination of R1 and R2 is?

A. 6.67%
B. 5.5%
C. 7.77%
D. 2.8%

View Answer

Question 9

The current flowing in a resistor of 1? is measured to be 25 A. But it was discovered that ammeter reading was low by 1% and resistance was marked high by 0.5%. Find true power as a percentage of the original power.

A. 95%
B. 101.5%
C. 100.1%
D. 102.4%

View Answer

Question 10

Two resistances 100 ± 5? and 150 ± 15? are connected in series. If the error is specified as standard deviations, the resultant error will be _________

A. ±10 ?
B. ±10.6 ?
C. ±15.8 ?
D. ±20 ?

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Question 11

A 0-400V voltmeter has a guaranteed accuracy of 1% of full scale reading. The voltage measured by this instrument is 250 V. Calculate the limiting error in percentage.

A. 4%
B. 2%
C. 2.50%
D. 1%

View Answer

Question 12

A 500 A, 50 Hz current transformer has a bar primary. The secondary burden is a pure resistance of 1 Ω and it draws a current of 5 A. If the magnetic core requires 250 Ampere-turn for magnetization, the percentage ratio error is __________

A. 10.56%
B. -10.56%
C. 11.80%
D. -11.80%

View Answer

Question 13

A resistor of 10 kΩ with the tolerance of 5% is connected in parallel with 5 kΩ resistors of 10% tolerance. What is the tolerance limit for a parallel network?

A. 9%
B. 12.40%
C. 8.33%
D. 7.87%

View Answer

Question 14

A voltmeter has a sensitivity of 1000 Ω/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The actual resistance of the unknown resistor will be?

A. 20 kΩ
B. 18.57 kΩ
C. 21.43 kΩ
D. 22.76 kΩ

View Answer

Question 15

A voltmeter has a sensitivity of 1000 Ω/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The apparent resistance of the unknown resistor will be?

A. 20 kΩ
B. 21.43 kΩ
C. 18.57 kΩ
D. 22.36 kΩ

View Answer

Question 16

A voltmeter has a sensitivity of 1000 Ω/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter. When the milliammeter reads 10 mA. The error due to the loading effect of the voltmeter is ________

A. 3.33%
B. 6.67%
C. 13.34%
D. 13.67%

View Answer

Question 17

Resistances R1 and R2 have respectively, nominal values of 10Ω and 5Ω and limiting error of ± 5% and ± 10%. The percentage limiting error for the series combination of R1 and R2 is?

A. 6.67%
B. 5.50%
C. 7.77%
D. 2.80%

View Answer

Question 18

The current flowing in a resistor of 1Ω is measured to be 25 A. But it was discovered that ammeter reading was low by 1% and resistance was marked high by 0.5%. Find true power as a percentage of the original power.

A. 95%
B. 101.50%
C. 100.10%
D. 102.40%

View Answer

Question 19

Two resistances 100 ± 5Ω and 150 ± 15Ω are connected in series. If the error is specified as standard deviations, the resultant error will be _________

A. ±10 Ω
B. ±10.6 Ω
C. ±15.8 Ω
D. ±20 Ω

View Answer