In the given potentiometer circuit, the wire AB is 3 m long and has resistance R = 4.5 Ω. Find the length AC for zero deflection in the galvanometer.

Question

G1 Physics · Accepted Answer

In a potentiometer, the balance point requires the potential drop along AC to equal the test-cell emf. Using the primary-circuit current from the shown battery and wire resistance gives a balance length that is not 2 m or 1.8 m and is not independent of the primary-cell internal resistance. Hence D.