Potentiometer

Why copper wire is not used in potentiometer?

What is the principle of potentiometer?

For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because

The length of a wire of a potentiometer is $100 \mathrm{cm}$, and the emf of its standard cell is $E \mathrm{volt}$. It is employed to measure the e.m.f. of a battery, whose internal resistance is $0.5 \mathrm{\Omega }$ . If the balance point is obtained at $l=30 \mathrm{cm}$ from the positive end, the emf of the battery is