A rheostat is a variable resistor used to control the flow of electric current. It is commonly used in applications such as dimming lights, controlling motor speed, and regulating the output of power supplies. A rheostat can be used as either a voltage divider or a current limiter, depending on the application. A rheostat is composed of a resistive element, a wiper, and a pair of contacts. The wiper is connected to one end of the resistive element, while the contacts are connected to the other end. As the wiper is moved, the resistance of the element is changed, and the amount of current flowing through the circuit is regulated.