Name the instrument used to control the current in an electric circuit.
The correct option is A Rheostat Rheostat is the instrument used to control the current in an electric circuit. It is an adjustable or variable resistor. It is used to control the electrical resistance of a circuit without interrupting the flow of current. Rheostat has 3 terminals and usually consist of a resistive wire wrapped to form a toroid coil with a wiper that slides along the surface of the coil. It is most often designed with a ceramic core. Rheostats are used in applications that require high voltage and current. The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors. Its resistance element can be a metal wire or ribbon, carbon, or a conducting liquid, depending on the application.