The circuit breaker will open, or "break", the circuit when the current in that circuit becomes too high, or the fuse will "blow". This gives protection.
The current flowing in an electrical or electronic circuit can suddenly increase when a component part fails. This can cause serious damage to other components in the circuit, or create a fire hazard. To protect against this, a fuse or a device called a "circuit breaker" can be wired into a circuit.
We use them in conjunction with solar-powered model car kits which students have to build themselves. These receive energy through solar powered panels allowing us also to teach ideas about renewable energy as well as electricity. The solar panels also allow us to integrate problem solving into lessons, with students having to investigate when panels work best.
A circuit or wiring diagram is a visual display of an electrical circuit.