Question

A voltage $V_0$ is applied to a potentiometer whose sliding contact is exactly in the middle. A voltmeter $V$ is connected between the sliding contact and one fixed end of the potentiometer. It is assumed that the resistance of the voltmeter is not very high in comparison to the resistance of the potentiometer wire. What voltage will the voltmeter show : higher than, less than, or equal to $V_0/2$?

Answer 1

$R=$ Resistance of whole potentiometer wire AB

$R_v=$ Resistance of voltmeter

$R_{AC}=$ Total Resistance across $AC$

$R_{AC}=\frac{R_v\left(R/2\right)}{R_v+\left(R/2\right)}=\frac{R}{2(1+R/2R_v)}<\frac{R}{2}$

The resistance of section CB is equal to $\frac{R}{2}$

So the reading of voltmeter will be less than $\frac{V_0}{2}$