Two students $X$ and Y perform potentiometer experiment separately and null point was obtained as shown in…
Two students $X$ and Y perform potentiometer experiment separately and null
point was obtained as shown in diagram. During the experiment,
(i) X increases the value of $\mathrm{R}$ (resistance)
(ii) Y decreases the value of S (resistance) without any other change
The position of null point obtained by students $\mathrm{X}$ and $\mathrm{Y}$ respectively
would shift towards $A$ by both $X$ and $Y$
would shift towards point A, would shift towards B
would shift towards $B$ by both $X$ and $Y$
would shift towards point $B$, would shift towards $A$
Solution
(1) With $R$ increase, the current $I$ will decrease, so potential gradient will increase. So larger length will be required for a null point.
(2) When $S$ is decreased the current drawn from $E_{1}$ increases.
So $\mathrm{V}=\mathrm{E}_{1}-\mathrm{Ir}$, the potential difference across $\mathrm{E}_{1}$ will decrease. This new potential difference will be balanced by a smaller length of potentiometer wire.
