Question

What is the main source of error in a null detector?

(a) lower current detection ability

(b) insufficient sensitivity of the null detector

(c) wiring resistance

(d) power dissipation

I got this question during an interview.

Question is from Measurement Errors in a Wheatstone Bridge in portion Measurement of Resistance of Electrical Measurements

Answer 1

Correct choice is (b) insufficient sensitivity of the null detector

To elaborate: Resistance of contact wires and power dissipation are some of the causes for error in a null detector. But insufficient sensitivity is the major source of error in a null detector such as a galvanometer.