Thermal radiation facts for kids
Thermal radiation is radiation that things make because they are warmer than what is around them. It may be felt as heat or seen as light. It is a form of heat transfer that is moved from one place to another by electromagnetic radiation. It does not require a form of matter to be transferred.
Thermal radiation can travel in all directions. Dark, dull surfaces give out more thermal radiation while bright, shiny surfaces give out less thermal radiation. Those surfaces which give out thermal radiation well also absorb thermal radiation well.
For example a person in front of a fire can warm up because of the heat of the fire, even if the air is cold. Another example of thermal radiation is the heat that comes from the Sun to the Earth.
Warmer things make more radiation, and the electromagnetic waves are shorter. Most things on Earth are warm enough to make infrared radiation. Incandescent light bulbs are so hot, their radiation includes visible light.
Interesting facts about thermal radiation
- Every surface or body that is above absolute zero (0 K or -273°C) radiates heat.
- Objects that are good emitters of thermal radiation are also good absorbers of it.
- The other two ways that thermal energy can be transferred are conduction and convection. Both need matter to transfer energy.
- Something does not have to be considered "hot" to radiate heat. It just has to be warmer than what surrounds it.
- Special cameras called thermal imaging cameras can be used to detect radiated heat.
- When a room is full of people, it may feel warmer because of all the thermal energy the people radiate.
Related pages
Images for kids
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Spectral response of two paints and a mirrored surface, in the visible and the infrared. From NASA.
See also
In Spanish: Radiación térmica para niños
