MP Board · Class 12 · Physics · Current ElectricityExplain the principle, construction, working, and uses of a potentiometer. Derive the formula used to compare the emfs of two primary cells using a potentiometer.

Principle of Potentiometer

The potentiometer works on the principle that the potential drop across any portion of a wire of uniform cross-section and constant composition is directly proportional to the length of that portion, provided a steady current flows through it. $$V propto l implies V = k cdot l$$ where $k$ is the potential gradient ($k = rac{V}{L}$).