Three resistances P, Q, R each of 2 and an unknown resistances S form the four arms of a Wheatstone bridge circuit. When a resistance of 6 is connected in parallel ot S the bridge gets balanced. What is the value of S ?

Step-by-step solution

The bridge formed with given resistances is a balanced Wheatstone's bridge The situation can be depicted as shown in the figure. As resistances (S ) and (6 ) are in paralle, their effective resistance is ( 6 S 6+S ). For balancing condition, ( P Q = R ( 6 S 6+S ) ) or ( 2 2 = 2(6+ S ) 6 ~S ) or (3 ~S =6+ S S =3 )