Question

For comparing the e.m.f,'s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful?

• A. The e.m.f. of the standard cell is larger than the $E$ e.m.f.'s of the two cells.
• B. The diameter of the wires is the same and uniform throughout.
• C. The number of wires is ten.
• D. The e.m.f. of the standard cell is smaller than the e.m.f.’s of the two cells.

Answer 1

Answer: (D)

The emf of the standard cell must be greater than that of experimental cells, otherwise balance point is not obtained.