Question

In the given potentiometer circuit, length of the wire $A B$ is $3 \,m$ and resistance is $R=4.5\, \Omega$. The length $A C$ for no deflection in galvanometer is

• A. 2 m
• B. 1.8 m
• C. dependent on $r_{1}$
• D. none of these

Answer 1

Answer: (A)

Potential gradient,
$x=\left(\frac{5}{0.5+4.5}\right)\left(\frac{4.5}{3}\right)=1.5\, V m ^{-1}$
Here $(x)(A C)=3$
$ \Rightarrow A C=\frac{3}{1.5}=2 m$