A Rheostat is an important lab instrument used for controlling current. It is a type of potentiometer. It consists of three terminals; while two terminals are connected by a fixed resistance, the third one has a variable resistance depending on the position.

It is a variable resistor, having a high-resistance wire-wound coil. The equipment is used to vary electrical resistance without interrupting the current. The resistance of the instruments to the current is dependent on the position of a mechanical element or control in the device.

A variable rheostat has a resistance element equipped with two terminals, attached to a circuit with the help of the terminals. while one end in the circuit is fixed, the other has a sliding contact. The current enters and exits the resistance element through the contacts. It is often used for controlling the speed of electric motors and in light dimmers.

Important Specifications to be Considered
There are certain electrical specifications that should be considered when buying a rheostat. Some of them are:

• Resistance range
• Resistance tolerance
• Resistance resolution
• Maximum DC and AC operating voltage

Use of Variable Rheostat
Rheostats find use in a number of applications including:

• Transducers
• Audio Systems
• Electronic Equipment