Four resistors are connected in a bridge form

PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity

Problem

Four resistors are connected in a bridge form. The resistances in the four arms are

R_1 = 120\,\Omega

(AB),

R_2 = 80\,\Omega

(BC),

R_3 = 150\,\Omega

(AD) and an unknown

R_4

(DC). A d.c. source of

10\,\text{V}

is connected between A and C, and a galvanometer of very high resistance is connected between B and D. (a) Calculate the value of

R_4

required so that the galvanometer shows zero deflection. (b) For the value of

R_4

obtained in part (a), verify by calculation that the potentials at B and D are equal when a current is drawn from the source.