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Thread: Black body radiation

  1. #1 Black body radiation 
    Forum Masters Degree thyristor's Avatar
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    Hi!
    I would like to know how I calculate the ratio between the energy of EM-radiation emitted in one wavelength interval and the energy of EM-radiation emitted in another wavelength interval, for a body with known temperature.
    I guess it involves Planck's law, but I'd be grateful if you could explain to me how.

    Will it be something like:
    , where w is the wavelength, and a,b,c and d are the llimits for the wavelength range?
    The only problem is I don't know how to calculate I' (I guess it means the derivative of I).


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  3. #2 Re: Black body radiation 
    . DrRocket's Avatar
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    Quote Originally Posted by thyristor
    Hi!
    I would like to know how I calculate the ratio between the energy of EM-radiation emitted in one wavelength interval and the energy of EM-radiation emitted in another wavelength interval, for a body with known temperature.
    I guess it involves Planck's law, but I'd be grateful if you could explain to me how.

    Will it be something like:
    , where w is the wavelength, and a,b,c and d are the llimits for the wavelength range?
    The only problem is I don't know how to calculate I' (I guess it means the derivative of I).
    http://en.wikipedia.org/wiki/Black_body


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  4. #3  
    Forum Masters Degree thyristor's Avatar
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    Ok, so I guess I was right in what I wrote. However, I still don't know how to calculate that integral of I' with primitive function.
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  5. #4  
    Forum Masters Degree thyristor's Avatar
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    I didn't know how to delete posts
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  6. #5  
    Forum Masters Degree thyristor's Avatar
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    Ok, so I plotted the graph I' in my calculator, and it looked weird. It peaked for wavelength close to zero, and din't lokk at all as it's supposed to be. Have you got any ideas of what might be wrong?
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