Physics Question from JEE Main 2023 · 1 February, Shift 1

In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf $1.5 \, \text{V}$ is found to be $60 \, \text{cm}$. If this cell is replaced by another cell of emf $E$, the length-of null point increases by $40 \, \text{cm}$. The value of $E$ is $\frac{x}{10}$ V. The value of $x$ is _____.