In the Figure below, R S is to be adjusted in value by moving the sliding contact across it until points a and b are brought to the same potential.

In the Figure below, R S is to beadjusted in value by moving the slidingcontact across it until points a and b arebrought to the same potential. (One testsfor this condition by momentarilyconnecting a sensitive ammeter betweena and b, if these points are at the samepotential, the ammeter will not deflect.)Show that when this adjustment is made,the following relation holds:21SxR RRR= . Anunknownresistance (R x )can be measuredin terms of astandard (R S )using this device,which is called aWheatstone bridge.