Waves: Infrared Radiation and Temperature

Infrared Radiation

Infrared radiation is a type of electromagnetic wave, situated between microwaves and visible light in the electromagnetic spectrum.
All objects emit and absorb infrared radiation. The hotter an object, the more infrared radiation it emits.
This kind of radiation does not need a medium to travel through and can pass through a vacuum, like all electromagnetic waves.

Temperature affects the amount of infrared radiation released by an object: at a higher temperature, more infrared radiation is emitted.
If an object is absorbing more infrared radiation than it is emitting, the object’s temperature will increase.
Similarly, if the object is emitting more infrared radiation than it is absorbing, the temperature of the object will decrease.

The emissivity of an object’s surface describes how efficiently that surface emits infrared radiation. Black surfaces are good emitters whilst shiny surfaces are generally poor emitters.
Infrared radiation can be detected using an infrared detector or through thermal imaging technology.
Thermal imaging cameras work by detecting the infrared radiation emitted by objects and converting this into an electrical signal which, when processed, produces a thermal image or ‘heat map’ on a screen.
Animals can be visualised at night using this kind of camera, as living bodies emit a lot of infrared radiation due to their heat.

Infrared radiation has multiple practical applications. It’s used in remote controls, for cooking (in toasters and grills), for infrared saunas, and in certain types of medical therapy.
Infrared radiation is also employed in security systems and in wildlife observation for tracking and monitoring species.