Consider the potentiometer circuit of Fig. The resistor between a and b is a uniform wire with length l, with a sliding contact c at a distance x from b. An unknown emf E2 is measured by sliding the contact until the galvanometer G reads zero.
(a) Show that under this condition the unknown emf is given by E2 = (x/l)E1
(b) Why is the internal resistance of the galvanometer not important?
(c) Suppose E1 = 9.15 V and l = 1.000 m. The galvanometer G reads zero when x = 0.365 m. What is the emf E2?