Potentiometer has multiple uses. It is based on the principle that when constant current flows through a wire of uniform area of cross-section then potential drop along its length is directly proportional to corresponding length.

i.e.  $V \propto I$

$V=K I$

Various uses of potentiometer on:

• To measure potential differences between any two points in an electrical network
• To compare emf of a cell
• To measure emf of a cell
• To measure internal resistance of a cell etc.

Answer the following question related to potentiometer:

In the given potentiometer the null point for the primary cell is obtained at P. The effect on the balancing length when resistance X is increased, will be:

Balancing length remains unchanged

The correct answer is Option (2) → Balancing length remains unchanged

The balancing length will remain unchanged as on increasing ‘X’ there is no change in emf of the battery.