Other Components
Fuse: Thin wire in series with the circuit. Melts (blows) if current exceeds its rating, opening the circuit to protect components. One-time use — must be replaced.
Switch: Opens or closes a circuit. Types: toggle, push-button (momentary), slide.
Relay: Electromagnetically operated switch. A small control current energizes a coil that opens or closes contacts carrying a larger current. Isolates control and power circuits.
Antenna: Radiates or receives electromagnetic waves for wireless communication.