State the underlying principle of a potentiometer. Write two factors on which the sensitivity of a potentiometer depends.
In the potentiometer circuit shown in the figure, the balance point is at $\mathit{X}$. State, giving reason, how the balance point is shifted when
(i) resistance $\mathit{R}$ is increased ?
(ii) resistance $\mathit{S}$ is increased, keeping $\mathit{R}$ constant?