In the electrical circuit shown in figure the current through the galvanometer will be zero if the value of resistance x is
The given circuit is Wheatstone's bridge.The current through the galvanometer will be zero if the bridge is balanced
PQ+RS where P = 2+3 =5 ohm, Q = 10 ohm and R=4 ohm
The value of S is given by
510=4S
or S= 8 ohm
thus the effective resistance of the parallel combination of 12 ohm and x ohm must be 8 ohm
therefore
112+1x=18
which gives x = 24 ohm