Question

In the potentiometer arrangement shown in figure, null point is obtained at length $l$ .
Table 1 Table - 2
(a) If $E_1$ is increased (p)$l$ should increase
(b) If R is increased (q) $l$ should decrease
(c) If $E_2$ is increased (r)$l$ should remain the same to again get the null point

• A. a - q, b - q, c - p
• B. a - r, b - r, c - q
• C. a - p, b - p, c - r
• D. a - q, b - p, c - p

Answer 1

Answer: (D)

a - q, b - p, c - p

When $E_1$ in increased , potential gradient across wire is increased. Thereby, it decreases the length to balance $E_2.$

If R is increased, potential gradient across wire in decreased. Thereby it increases the length to balance $E_2$.

When $E_2$ is decreased, it decreases the balancing length.