Kirchhoff S Laws

Let be the total current passing through balanced Wheatstone bridge. Current through arms of resistances and in series is


and current through arms of resistances and in series is

Ratio of heat developed per sec

The correct answer is A:
The balanced condition for Wheatstone's bridge is
as is obvious from the given values. No, current flows through galvanometer is zero.
Now, and are in series, so
Resistance

Similarly, and are in series,
so Resistance

Net resistance of the network as and are in parallel


Hence,