In a relay, what happens when the circuit is energized?

• A. The relay remains inactive
• B. The relay opens the circuit
• C. The relay closes the circuit
• D. The relay generates feedback

Answer: (C)

When the circuit is energized, the correct outcome is that the relay closes the circuit. A relay is an electromechanical switch that utilizes an electromagnet to create a magnetic field when voltage is applied. This magnetic field attracts a movable armature, which in turn connects (or closes) the contacts of the relay. As a result, the circuit through which the relay controls becomes complete, allowing current to flow.

This action is crucial in many applications where low-power signals control high-power circuits. By closing the circuit, the relay allows the controlled device, such as a motor or light, to operate. Understanding this function is essential for designing circuits that require isolation between different sections or controlling devices with varying voltage levels.