Meter Bridge or Slide Wire Bridge—

it is an arrangement based on the principle of Wheatstone Bridge used to measure an unknown resistance.

Construction—

Wheatstone Bridge—

It is arrangement of four resistances used to determine one unknown resistance with the help of remaining three resistances.

In this arrangement we arrange four resistances P, Q, R and S as shown in figure.

On applying Kirchhoff’s Law

Application of a Potentiometer—

1. Measurement of emf of a cell
2. Comparison of emfs of two primary cell
3. Measurement of Internal Resistance if a cell

Measurement of emf of a cell—

Potentiometer—

A potentiometer is a device used to measure the potential difference between two points or the unknown emf.

Principle-

When a uniform current flows through a uniform wire the potential drop across any length is directly proportional to the length of the wire.

Construction-