Question

In the meter bridge experiment shown in figure, the balance length AC corresponding to null deflection of the galvanometers is x. What would be the balancing length if the radius of the wire AB is doubled?

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

Answer 1

The correct option is B x

The condition for no deflection of the galvanometer is
$\frac{R_1}{R_2}=\frac{R_{AC}}{R_{CB}}$
Where $R_{AC}$ and $R_{CB}$ are the resistances of the bridge wire of length AC and CB respectively. If the radius of the wire AB is doubled, the ratio $\frac{R_{AC}}{R_{CB}}$ will remain unchanged. Hence the balance length will remain the same. Thus, the correct choice is (b).