How does a rheostat differ from a potentiometer?

A rheostat typically has two terminals, allowing it to function as a variable resistor, which is primarily used to control current in a circuit. In contrast, a potentiometer has three terminals and is designed to adjust electrical voltage levels rather than current. The middle terminal is used to draw a specific voltage from the total applied voltage between the two outer terminals.

Because of this design, rheostats are usually employed in applications where only current control is needed, such as dimming lights or controlling motors. This distinction is essential for understanding their respective functionalities, making the choice about the terminal count correct.