In this deck, we'll explore thermal radiation. You'll learn how all objects give off and take in heat in the form of infrared waves, why a dark-coloured t-shirt gets hotter in the sun than a light-coloured one, and what physicists mean by a 'perfect black body'.

Let's begin with a fundamental principle. All objects with a temperature above absolute zero are constantly emitting and absorbing thermal radiation. This radiation is primarily in the form of infrared waves, which are part of the electromagnetic spectrum.

An object's temperature has a major effect on this process. If an object is hotter than its surroundings, it emits more radiation than it absorbs, which causes it to cool down. The key point to remember is that the hotter an object is, the more infrared radiation it emits per second.

The nature of an object's surface is also very important. Dark, matt surfaces are excellent absorbers of infrared radiation. This is why a black pavement can get extremely hot on a sunny day. These surfaces are also excellent emitters of radiation.