Question

In the shown arrangement of the experiment of a meter bridge, if length of $\text{AC}$ corresponding to null deflection of galvanometer is $x$, what would be its value if the radius of the wire $\text{AB}$ is doubled ?

• A. $x$
• B. $\frac{x}{4}$
  
• C. $4x$
• D. $2x$

Answer 1

The correct option is A $x$

At null point,

$\frac{R_1}{R_2}=\frac{x}{(100-x)}$

If radius of the wire is doubled, then the resistance of $\text{AC}$ will change and the resistance of $\text{CB}$ will also change. But since $\frac{R_1}{R_2}$ does not change, so$\frac{x}{100-x}$ should also not change at null point.

Therefore, point $\text{C}$ does not change.

Hence, option $\left(a\right)$ is the correct answer.