Question

Which is not a source of error in the measurement of low resistance?

(a) contact resistance drops at the leads

(b) thermal e.m.f

(c) temperature effect

(d) power dissipation through the circuit

I got this question during an interview for a job.

This is a very interesting question from Measurement of Low Resistance in section Measurement of Resistance of Electrical Measurements

Answer 1

Correct answer is (a) contact resistance drops at the leads

To explain I would say: As the current flowing through a low resistance circuit is low, the voltage drop across the terminals due to contact and lead resistances is negligible. Thermal e.m.f occurs in a circuit when its temperature increases due to high current flow.