What is the function of a rheostat?

A rheostat functions primarily to regulate current flow in a circuit. This is achieved by varying its resistance, which directly influences the amount of current that can pass through it. By adjusting the resistance, the rheostat can increase or decrease the current, allowing for finer control of electrical devices, such as dimming lights or controlling the speed of motors.

In contrast, measuring voltage is not a function of a rheostat. That is typically the job of a voltmeter. Storing electrical energy is done by capacitors or batteries, rather than by rheostats. Measuring resistance is the primary function of an ohmmeter. Understanding these points clarifies that the correct choice focuses on the rheostat's essential role in controlling current flow rather than other functions associated with electrical measurements or storage.