Two potentiometer wires W1and W2 of equal length l connected to a battery of emf Ep and internal resistance ‘r’ through two switches S1 and S2. A battery of emf E is balanced on these potentiometer wire W1 is of resistance 2r and balancing length on W1 is l/2 when only switch S1 is closed and S2 is open. On closing S2 and opening S1 the balancing length on W2 is found to be 2l/3, the resistance of the potentiometer W2 will be