Question

32. If the value of S in the diagram is increased then balancing point will shift towards(metre bridge)
(a) Towards A
(b) Towards B
(c) remain in same position
(d) cannot say ​

Answer 1

Answer:

(i) If resistance R is increased, the balance point shifts towards B, because when R is increased current flowing in the circuit will decrease and the potential drop per unit length also decrease, so balance length will increase. (ii) If S is increased, there is no effect on the null point.

Answer 2

If the value of Resistance S in the diagram is increased then the balancing point will shift towards A. (Option a)

• The DC potentiometer technique of resistance measurement determines the unknown resistance of a low value.

• We use the formula  $S = \frac{100-l}{l} * R$  to measure the unknown resistance S.
• Moreover, we can see through the relation that if there is an increase in the value of S without any change in R, we have to increase the value of (100-l), which is the same as decreasing the value of l.
• Thus, to increase the value of Resistance S, the length l needs to be decreased. The same is done by shifting the null point towards the left or towards A.