A bridge network has resistances (AB), (BC), (AD), (DC) and a galvanometer of…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits
Problem
A bridge network has resistances R1 (AB), R2 (BC), R3 (AD), R4 (DC) and a galvanometer of resistance G connected between B and D. A steady voltage V is maintained between A and C.
(a) Considering the currents in all five branches to be unknown, write the independent loop equations and the junction equation required to solve the circuit.
(b) Eliminate the branch currents to derive an expression for the current Ig through the galvanometer in terms of R1,R2,R3,R4,G and V.
(c) Using your result, show that Ig becomes zero when R2R1=R4R3.