Difference between revisions of "Black Body Radiation"
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: 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. | : 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'''. | : [[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]]. | ||
Revision as of 15:06, 24 February 2019
Key Stage 4
Meaning
Black body radiation is the electromagnetic radiation given off by all objects with a temperature above absolute zero (0 Kelvin or -273°C).
About Black Body Radiation
- All objects emit electromagnetic waves.
- The frequency of electromagnetic wave depends upon the temperature of the object. The higher the temperature the higher the frequency of electromagnetic wave.
- The Sun emits visible light because its temperature is so high.
- Objects at room temperature emit Infra-red radiation. This can be seen using a thermal imaging camera.
- The colour of an object affects the rate at which it absorbs or emits infra-red radiation. Dark colours both absorbs and emit infra-red radiation more quickly than light colours.
- Reflective surfaces emit the least black body radiation.
- When the rate of emission and absorption are the same then an object will remain at a constant temperature. If the rate of emission is greater than the rate of absorption then the object will decrease in temperature. If the rate of emission is less than the rate of absorption then the object will increase in temperature.