Question

Figure (i) below shows a Wheatstone’s bridge in which P, Q, R and S are fixed resistances, G is a galvanometer and B is a battery. For this particular case, the galvanometer shows zero deflection. Now, only the positions of B and G are interchanged, as shown in figure (ii). The new deflection of the galvanometer

(a) is to the left

(b) is to the right

(c) is zero

(d) depends on the values of P, Q, R and S

Answer 1

Answer is : (c) is zero

In case (i), galvanometer shows zero deflection.

When battery B and galvanometer G are interchanged, position of galvanometer is as shown below,

Now, ratio of resistances across galvanometer is

Hence, galvanometer still shows zero deflection because Wheatstone’s bridge is balanced.