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Homework Help: Leslie Cube (still)

  1. Jan 24, 2005 #1
    sorry, this was my question from yesturday, and now my assignment is due tomorrow. anyone have any help for me?

    A Leslie cube has a surface temp of 97C. One of its four side faces has an area of 100 cm^2 and is painted black. Calculate:

    a) the wavelength at which the spectral intensity (per unit wavelength) is a maximum

    b)the total intensity (all wavelengths) of the emitted radiation just outside the surface

    C) the total power emitted by the black surface

    for a) i used lambda=2.9*10^-3/T (not sure if this is the correct way of doing it)

    for b) i wanted to use Stefan's Law but this seems to simple

    for c) i multiplied the answer from b) by the area of the four sides.

    does any of this sound correct? i seem to be struggling on this topic

    also, in Planck's energy density equation, what exactly is the spectral energy density? is it also known as anything else? thanks.
  2. jcsd
  3. Jan 24, 2005 #2


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    You did the problem wery well,all three points of it... :smile:

    The volumic spectral energy density (given by Planck's law) has the significance of the thermal radiation/unit of volume in one domain/interval of frequency chosen equal to unity...

  4. Jan 24, 2005 #3


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    One more thing to point a) of the problem.I sincerely hope u converted the Celsius degrees into Kelvin ones... :uhh:

  5. Jan 24, 2005 #4
    thanks for your input on this. glad to here i did it correctly, and of course i converted to kelvin, thanks for the heads up though
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