Question

In post office box, the graph of galvanometer deflection versus resistance R (pulled out of resistance box) for the ratio 100 : 1 is given as shown (due to unsuitable values of R, galvanometer shows deflection). The two consecutive values of R are shown in the figure.

The value of unknown resistance would be

(a) 3.2 ohm

(b) 3.24 ohm 

(c) 3.206 ohm

(d) 3.237 ohm

Answer 1

Correct Option (b) 3.24 ohm

Explanation:

For post office box (Wheatstone bridge), under balanced conditions

From the given graph, the galvanometer shows zero deflection at