Physics - Current Electricity Question with Solution | TestHub

Potential Difference of external circuit$=\mathrm{ }\mathrm{\varphi }\times$balancing length

$\frac{\mathrm{E}}{2}=\left(\frac{\mathrm{E}}{\mathrm{L}}\times \frac{{\mathrm{R}}_{\mathrm{p}}}{{\mathrm{R}}_{\mathrm{p}}+\mathrm{r}}\right)\times \mathrm{l}$

$\Rightarrow \frac{\mathrm{E}}{2}=\frac{\mathrm{E}}{600}\times \frac{15\mathrm{r}}{16\mathrm{r}}\times \mathrm{l}$

$\therefore \mathrm{ }\mathrm{l}=\frac{600\times 16}{30}=320\mathrm{ }\mathrm{c}\mathrm{m}$