Which component is used to interrupt a circuit when current exceeds safe levels?

• A. A device that allows current to flow when the circuit is closed
• B. A coax cable
• C. Fuse
• D. Push button switch

Answer: (D)

Overcurrent protection stops current flow when it’s dangerous for the circuit. A fuse is designed for this exact purpose: it contains a thin metal link that melts and opens the circuit when the current exceeds its rating, preventing damage. This automatic interruption happens without user action, which is what you need for protecting components.

The other options don’t provide automatic protection. A device that simply allows current to flow when the circuit is closed is just a switch or conductor—no automatic response to high current. A coax cable is just a transmission path, not a protective component. A push button switch is a manual control that interrupts the circuit only when you press it, not in reaction to overcurrent.