Potentiometer is a device which is mainly used

1. To measure EMF of cell.

2. An unknown resistance.

Basically it has more length then meter bridge and more accurate henceforth.

U shhud refer HCV...Although u can clear concept abt it only frm a teacher ie face to face teaching.

I also had probs. when in XII ...but in my drop year i consulted a teacher and got it cleared.

Consult a gud physics teacher...

the basic principle of potentiometer is that when a stady current is passed through a wire of uniform cross-section then the resistance per unit length of the wire is directly proportinal to length of the wire

A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider.^[1] If only two terminals are used (one side and the wiper), it acts as a variable resistor or Rheostat. Potentiometers are commonly used to control electrical devices such as a volume control of a radio. Potentiometers operated by a mechanism can be used as position transducers, for example, in a joystick.

It is an ideal volt meter.It works on the principle of potential drop per unit length.It is very absolute and error percentage is very small