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Radiant energy

  1. Jan 13, 2010 #1
    Hi guys, I was reading through some Chemistry papers when I came across these two lines; When solids are heated, they emit electromagnetic radiation over a wide range of wavelengths. The amount of radiation energy emitted by an object at a certain temperature depends on its wavelength. However, I remember reading elsewhere that the radiant energy of an electromagnetic wave increases as its frequency increases. If this is true, then the two statements are my understanding is contradictory with the two lines. Am I misinterpretting the two lines from the Chemistry papers or is there something else I am not realising? Any help is much appreciated.
     
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  3. Jan 13, 2010 #2

    vela

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    The frequency [itex]f[/itex] and wavelength [itex]\lambda[/itex] of light are related by [itex]\lambda f = c[/itex] where c is the speed of light.
     
  4. Jan 16, 2010 #3
    Thanks for the help, but how can I relate that to the question? What I mean is that the two earlier equations are contradictory since one says that the energy of wave depends in its frequency while the other says that the amount of energy of the wave depends on its wavelength. Which of these is true or is my interpretation wrong? Thanks for the help anyway.
     
  5. Jan 16, 2010 #4

    vela

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    Wavelength and frequency are not independent parameters. Knowing one is equivalent to knowing the other, so you can express the energy in terms of either. For example, the energy of a photon can be written

    [tex]E=hf=\frac{hc}{\lambda}[/tex]

    where [itex]h[/itex] is Planck's constant and [itex]c[/itex] is the speed of light.
     
  6. Jan 16, 2010 #5
    From the equation, do you mean that frequency is proportional to the energy of a type of light (like infrared of ultraviolet) while wavelength is inversely proportional so the statements that 'When solids are heated, they emit electromagnetic radiation over a wide range of wavelengths. The amount of radiation energy emitted by an object at a certain temperature depends on its wavelength' are wrong? Thanks for the help by the way.
     
  7. Jan 16, 2010 #6
    The amount of blackbody radiation at a given wavelength depends on the object's temperature.

    See [URL [Broken] Law[/url]

    Objects at higher temperatures emit more light at a shorter wavelength (higher frequency).
     
    Last edited by a moderator: May 4, 2017
  8. Jan 16, 2010 #7

    vela

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    No. Why would what I said imply that that statement is wrong?
     
  9. Jan 16, 2010 #8
    Oh I get what you guys mean. I was interpretting the statements wrongly. K, thanks for the help. It's really appreciated.
     
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