In meter bridge experiment, null point was obtained at a distance ' $l$ ' from left end. The values of…
In meter bridge experiment, null point was obtained at a distance ' $l$ ' from left end. The values of resistances in the left and right gap are doubled and then interchanged. The new position of the null point is
$(100-l)$
$(100-2 l)$
$(100-3 l)$
$\left(100-\frac{l}{2}\right)$
Solution
$\begin{aligned}
& \text { For a Metre bridge, } \\
& \frac{\mathrm{X}}{\mathrm{R}}=\frac{l_{\mathrm{X}}}{l_{\mathrm{R}}}
\end{aligned}$
After doubling and interchanging the left and right gap resistances, the ratio of the resistances do not change.
This means the null point does not change.
$\therefore \quad$ The new position will remain at $(100-l)$.