What is a rheostat?

A rheostat is a device used to vary the resistance in an electrical circuit. This functionality allows it to control the current flowing through the circuit without interrupting the circuit itself. Rheostats are particularly useful in applications where adjustments to the brightness of lights, speed of motors, or temperature of heating elements are needed. By changing the resistance, a rheostat can effectively manage the voltage and current, thus enabling fine-tuning of various electrical parameters in circuits.

The other options do not accurately describe a rheostat or its function:

• Some may confuse the term with devices like ammeters, which measure current but do not vary resistance.

• Devices that measure hertz are used for frequency measurement, which falls into a different category of electrical instrumentation.

• The idea of a specialized mobile phone for construction workers is unrelated to the concept of a rheostat. It does not pertain to electrical resistance or circuit management in any way.