Physics Question from JEE Main 2026 · 28 January, Shift 1

In the potentiometer, when the cell in the secondary circuit is shunted with $4\,\Omega$ resistance, the balance is obtained at a length $120\,\text{cm}$ of wire. Now when the same cell is shunted with $12\,\Omega$ resistance, the balance is shifted to a length of $180\,\text{cm}$. The internal resistance of the cell is _____ $\Omega$.