Which component is primarily responsible for controlling higher power circuits?

The relay is primarily responsible for controlling higher power circuits due to its ability to isolate and switch larger currents and voltages safely. Relays utilize an electromagnetic mechanism that allows a low-power signal to control a larger load, functioning as a switch that opens or closes based on the input current.

When a small voltage is applied to the relay's coil, it generates a magnetic field, which subsequently pulls a metal armature, closing a set of contacts. This operation allows the relay to control a significant amount of power in the circuit it switches, making it ideal for applications where a low-power control signal operates high-power devices, such as motors or heavy machinery.

While transistors can also switch electrical signals and can be used for high power in specific configurations, they are generally more suited for low to moderate power applications and do not offer the same level of isolation or control over high voltages as relays do. Resistors and capacitors serve very different purposes in electronic circuits; resistors primarily limit current, while capacitors store and release energy, neither being suitable for controlling higher power circuits in the same way that relays do.