Black body radiation

​​In a nutshell   

A perfect black body absorbs all radiation that hits it. Objects emit all types of electromagnetic radiation. Black body radiation is the spectrum of light emitted by an object.

Black body

​​Definition

A perfect black body is an object that absorbs all the radiation that hits it. No incident radiation is reflected or transmitted by a perfect black body.

Example

A cavity with a small hole in it. Light will enter through the hole and reflect inside the object. The hole is so small that it won't travel back outside.

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Black body radiation

Objects emit all types of electromagnetic radiation due to their thermal energy stores. A perfect black body is the best emitter of radiation.

Example

The ocean is an example of another black body as it absorbs the majority of visible light and radiates energy in the near-infrared and far-infrared.  It's not a perfect black body as it reflects some visible light.

Black body radiation is the spectrum of light emitted by an object. This depends on the temperature of the object.

Intensity is the power radiated (given off) per unit area of the object. The intensity of each wavelength of EM radiation emitted can be seen using a graph. The graph's curve changes depending on the temperature of the object.