What is heat radiation?

Heat radiation is invisible but you can feel it if it is strong enough. When you feel the heat from an electric fire you are feeling heat radiation or "infra-red" radiation.

Piglets kept warm with a heat lamp	Mmmmmmm, sausages.	Your TV remote emits an infra red signal

Infra red is actually just a colour that you cant see. When light passes through a prism it is split into light of different wavelengths. The colours we can see are ROYGBIV. Infra red is just before red. (Ultra Violet is just after violet).

There are special cameras that can "see" in the dark by detecting infra red radiation.

Hot objects emit heat radiation. The plate of chips below will emit heat radiation and cool down. Its temperature will fall.

Cold objects absorb heat radiation. The ice cream below will absorb heat radiation and get warmer. Its temperature will rise.

Later we will learn about what affects how quickly things emit or absorb heat radiation.

Infra red radiation can travel through empty space. We get a lot of heat radiation from the Sun so it must be able to travel through space.