The given circuit shows a uniform straight wire $A B$ of 40 cm length fixed at both ends. In order to get zero reading in the galvanometer $G$, the free end of $J$ is to be placed from $B$ at:

• A

  32 cm
• B

  8 cm
• C

  16 cm
• Correct answer
  D

  24 cm

Solution

$\frac{8}{x}=\frac{12}{40-x}$ $\frac{2}{x}=\frac{3}{40-x}$ $80-2 x=3 x$ $16=x$ from B $=40-16=24 \mathrm{~cm}$

Hence, the correct answer is option: 'D'.