How do light bulbs work, and why do onions give you bad breath?

We explore the curious questions that science can answer

Let there be light: the combination of a filament and a vacuum is illuminating (Getty/iStock)

How do light bulbs work?

A light bulb contains a thin wire filament. When a current flows through this filament, the metal heats up and then glows, giving out light. As the inside of the light bulb is a vacuum, there’s no oxygen to oxidise the filament, so it lasts a long time.

How does a radiator work?