Each of the resistances in the network shown in fig in equal to ,R. The resistance between the terminals A and B is

The equivalent circuit is shown the fig. Since the Wheatstone's bridge is balanced, therefore no current will flow through the arm KL. Equivalent resistance between AKM = R+R= 2R Equivalent resistance between ALM = R+R= 2R The two resistances are in parallel. Hence equivalent resistance between A and B is given by1R′=12R+12R=22R=1RR′=R