With the help of potentiometer, we can determine the value of emf of a given cell. The sensitivity of the potentiometer is
(A) directly proportional to the length of the potentiometer wire
(B) directly proportional to the potential gradient of the wire
(C) inversely proportional to the potential gradient of the wire
(D) inversely proportional to the length of the potentiometer wire
Choose the correct option for the above statements:
Answer: (B) A and C only
A potentiometer is more sensitive when a small change in voltage gives a large change in balancing length, i.e. when the potential gradient $k=\dfrac{V}{L}$ is small. So sensitivity $\propto\dfrac1k\propto L$ (for a given voltage across the wire).
A and C are correct.
Solution by Sreeraj P, M.Sc Physics