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==Key Stage 4==
===Meaning===
[[File:BlackBodyRadiationSpectrum.png|right|300px|thumb|This is a [[graph]] of the [[Black Body Radiation Spectrum|'''black body radiation''' [[spectrum]] for several [[temperature]]s.]]
'''Black body radiation''' is the [[Electromagnetic Wave|electromagnetic radiation]] given off by all [[object]]s with a [[temperature]] above [[Absolute Zero|absolute zero]] (0 Kelvin or -273°C).
: The [[frequency]] of [[Electromagnetic Wave|electromagnetic wave]] depends upon the [[temperature]] of the [[object]]. The higher the [[temperature]] the higher the [[frequency]] of [[Electromagnetic Wave|electromagnetic wave]].
: The [[Sun]] [[emit]]s [[Visible Light|visible light]] because its [[temperature]] is so high.
: [[Object]]s at [[Room Temperature|room temperature]] [[emit]] [[Infra-red]] [[radiation]]. This can be seen using a [[Thermal Imaging|thermal imaging camera]].
: The [[colour]] of an [[object]] affects the rate at which it [[Absorb (Physics)|absorbs]] or [[emit]]s [[infra-red]] [[radiation]]. Dark [[colour]]s both [[Absorb (Physics)|absorbs]] and [[emit]] [[infra-red]] [[radiation]] more quickly than [[light]] [[colour]]s.
: [[Reflectivity|Reflective]] surfaces [[emit]] the least '''black body radiation'''.
: When the rate of [[emission]] and [[Absorb (Physics)|absorption]] are the same then an [[object]] will remain at a constant [[temperature]]. If the rate of [[emission]] is greater than the rate of [[Absorb (Physics)|absorption]] then the [[object]] will decrease in [[temperature]]. If the rate of [[emission]] is less than the rate of [[Absorb (Physics)|absorption]] then the [[object]] will increase in [[temperature]].