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 load of an electrical circuit may be as simple as those that power home appliances like refrigerators, televisions, or lamps or more complicated, such as the load on the output of a hydroelectric power generating station.
Schematics use symbols to represent components in the circuit. Conventions are used in a schematic to represent the way electricity flows. The common convention we use is from the positive to the negative terminal. The realistic way electricity flows is from the negative to the positive terminal.