Question

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 X. State, giving reason, how the balance point is shifted, when :

(i) resistance R is increased ?

(ii) resistance S is increased, keeping R constant ?

Answer 1

Principle of potentiometer : Fall of potential across any-portion of a w.ire is directly proportional to the length of that portion provided the wire is of uniform area of cross-section and current passing through it is constant.

There are two {actors on which the sensitivity of a potentiometer depends, i.e.,

(a) length of potentiometer (l)

(b) potential drop (E)

(i) If R increases, the potential gradient V/l decreases.

(ii) If S increases the potential difference increases