Question

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

(a) 9%

(b) 12.04%

(c) 8.67%

(d) 6.67%

This question was posed to me during an online interview.

The doubt is from Advanced Problems on Error Analysis in Electrical Instruments topic in chapter Measurement of Resistance of Electrical Measurements

Answer 1

Correct choice is (d) 6.67%

Explanation: Error in 10 kΩ resistance = 10 × \( \frac{5}{100}\) = 0.5 kΩ

Error in 5 kΩ resistance = 5 × \( \frac{10}{100}\) = 5 kΩ

Total measurement resistance = 10 + 0.5 + 5 + 0.5 = 16 kΩ

Original resistance = 10 + 5 = 15 kΩ

Error = \( \frac{16-15}{15}\) × 100 = \( \frac{1}{15}\) × 100 = 6.67%.