Question

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

• A. $x$
• B. $x/4$
• C. $4x$
• D. $2x$

Answer 1

The correct option is A $x$

At null point $\frac{R_1}{R_2}=\frac{R_3}{R_4}=\frac{x}{100-x}$
If radius of the wire is doubled, then the resistance of $AC$ will change and also the resistance of $CB$ will change.
But since $\frac{R_1}{R_2}$ does not change so, $\frac{R_3}{R_4}$ should also not change at null point. Therefore the point $C$ does not change.