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confuzzled92
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How does the area under a graph of relative intensity against wavelength give total power output?
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Stonebridge
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(Original post by confuzzled92)
How does the area under a graph of relative intensity against wavelength give total power output?
Relative intensity and wavelength of what, where, when? More info please.
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confuzzled92
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(Original post by Stonebridge)
Relative intensity and wavelength of what, where, when? More info please.
for black body spectra?
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Stonebridge
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The usual black body graph shows the curve representing how the output energy from the body varies with wavelength. (Usually in conjunction with Stefan's Law.)
The vertical axis of this graph (whose area gives the "total power output") is such that is shows the energy E_\lambda radiated per unit time, per unit surface area, in a small wavelength interval \delta\lambda.
If you integrate that function from lambda = 0 to infinity
You get E = \int^\infty_0 E_\lambda\ d\lambda

which is the total energy output per unit area per unit time.
That integral is the area under the curve.
It's the basis of Stepfan's Law
E = \sigma T^4
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