Question

Circuit shows the method of Measurement of low resistance by Ammeter-Voltmeter method. The measured resistance Rm for the given Circuit is _________

(a) Rx + Rv

(b) \(\frac{R_x^2}{R_x + R_v}\)

(c) \(\frac{R_v^2}{R_x + R_v}\)

(d) \(\frac{R_x R_v}{R_x + R_v}\)

This question was posed to me in a job interview.

The above asked question is from Advanced Problems on Measurement of Low Medium and High Resistance in chapter Measurement of Resistance of Electrical Measurements

Answer 1

Correct option is (d) \(\frac{R_x R_v}{R_x + R_v}\)

The best explanation: Measured resistance Rm = \(\frac{V_x}{I_A} = \frac{V_x}{I_v + I_R}\)

\(\frac{I_v}{V_x} =  \frac{1}{R_v}\) And \(\frac{I_R}{V_x} = \frac{1}{R_X}\)

So, Rm = \(\frac{R_x R_v}{R_x+R_v}\).