Waves: Infrared Radiation and Temperature

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.

Infrared and Temperature

  • 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.

Understanding and Measuring Infrared Radiation

  • 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.

Practical Uses of Infrared Radiation

  • 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.