Introduction to Blackbody Radiation


– Blackbody is a theoretical object that absorbs 100% radiation.
– Carbon in graphite form absorbs all but about 3% of incoming radiation.
– At a particular temperature the black body would emit the maximum amount of energy possible for that temperature. This value is known as blackbody radiation.

– Maximum wavelength emitted by a black body radiator is infinite
– Blackbody emits a definite amount of energy at each wavelength for a particular temperature.

Black Body Radiation Curves
Fig 1. Black Body Radiation Plot

– According to Figure 1, the curve touches the x-axis at infinite wavelength. This shown that blackbody does radiate energy at every wavelength.
– At 5800K the peak wavelength (wavelength that emits most energy) is about 5e-7 m.

Black Body Radiation Curves
Fig 2. Black Body Radiation Curves

– Figure 2 shows how the blackbody radiation curves change at various temperatures.
– As the temperature increases, the peak wavelength emitted by the blackbody decreases.
– As the temperature increases, the total energy emitted increases, because the total area under the curve increases.


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