Fuses protect houses by melting and breaking the circuit when too much current passes.

The longer version

A fuse contains a short piece of metal chosen to melt at a modest temperature. Current passing through any conductor generates heat, and the larger the current the more heat appears. If the flow grows beyond what the wiring can safely carry, that strip melts first and opens the gap.

Opening the path stops the flow instantly, protecting cables and appliances from overheating. The melting point and thickness of the strip set how much current is tolerated. Circuit breakers perform the same job with a mechanical switch that can be reset afterwards, while older installations relied on replaceable wire links instead.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.

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More From Science and Physics

Eight more entries

Batteries store chemical energy and release it as electricity when connected in a circuit.

A volt measures electrical push, while an amp measures how much charge flows.

The meter was originally defined as one ten-millionth of the distance from equator to pole.

A kilogram was once defined by a physical cylinder kept in a vault in France.

Celsius sets freezing at zero and boiling at one hundred for pure water at sea level.

Absolute zero is the coldest possible temperature, where particles nearly stop moving altogether.

An atom is mostly empty space, with tiny electrons orbiting a dense central nucleus.

Molecules in a gas move freely, while those in a solid only vibrate in place.

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