What device regulates the strength of an electrical current?

The device that regulates the strength of an electrical current is a rheostat. A rheostat is a type of variable resistor that can adjust resistance within an electrical circuit, thereby controlling the flow of current. By changing its position, the rheostat alters the resistance and, consequently, the amount of current that can pass through the circuit, making it an effective tool for adjusting the intensity of electrical devices such as lights or heating elements.

Transformers function to change the voltage of an electrical current but do not control the strength of the current itself. Capacitors store electrical energy and release it when needed, but they do not adjust the current flow in the same way a rheostat does. Diodes allow current to flow in one direction but do not provide a means to regulate its strength. Thus, when it comes to controlling and adjusting the strength of an electrical current, a rheostat is the correct device to identify.