Black Body Radiation
- Black body radiation is the name given to the thermal radiation emitted by all bodies (objects)
- All objects, no matter what temperature, emit black body radiation in the form of electromagnetic waves
- These electromagnetic waves usually lie in the infrared region of the spectrum but could be emitted in the form of visible light or other wavelengths, depending on the temperature
- The hotter object, the more infrared radiation it radiates in a given time
The infrared emitted from a hot object can be detected using a special camera
- A perfect black body is defined as:
An object that absorbs all of the radiation incident on it and does not reflect or transmit any radiation
- Since a good absorber is also a good emitter, a perfect black body would be the best possible emitter too
- As a result, an object which perfectly absorbs all radiation will be black
- This is because the colour black is what is seen when all colours from the visible light spectrum are absorbed
Absorption and Emission For Different Colours Table