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2. The Fuse

If an electrical appliance such as a kettle, microwave or record player stopped working, what would you do?

First, you might check the fuse.

Fuses are commonly found inside electrical plugs.

The purpose of the fuse is to protect the delicate, low voltage electronics found inside all electrical appliances. It prevents too much electricity flowing into the appliance if a fault occurs, such as a wire coming loose. If the flow of electricity becomes greater than a certain level, the fuse will "blow".

The fuse is really a thin wire inside a glass or ceramic cartridge.

When the fuse "blows" the thin wire melts and the electricity supply to the appliance is cut off. Some fuses, usually the low voltage ones, have a glass cartridge and you will be able to see if the wire inside is broken. The fuse inside most household appliance plugs, however, is usually a ceramic cartridge and you will not be able to see the wire inside. It is for this reason that a fuse tester is needed.

Fuses are quite delicate. If the fuse is old, or it has been dropped, it could "blow" even if there is no fault in the appliance

Further Reading
Electrical Safety: Some Simple Precautions

Exercises
Operations in Sequence: Wiring a Plug
Operations in Sequence: Electrical Safety

1: The Plug
3: The Problem

The Starting Point

The Pivot Point