**JEE Advanced 2008 Paper 1, Question 25**

The figure below shows three resistor configurations R1, R2 and R3 connected to battery. If the power dissipated by the configuration R1, R2 and R3 is P1, P2 and P3 respectively, then

**Solution**

The power dissipated by a resistance network is

(1)

The potential applied to all three networks arre the same, so we just need to find the resistances. Of circuits R2 and R3, the latter has a greater resistance since

(2)

whereas

(3)

The first circuit can be redrawn in the following way to make the comparison easier.

From the second figure we see that the network R1 is a perfectly balanced Wheatstone bridge, which means no current flows through the resistance connected between points and . We can also argue this by symmetry of the circuit, similar to what we did for this problem. Therefore, the network has an effective resistance

(4)

Therefore , which means **option (C) is correct**.