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Question: Calculate Wavelength from Intensity

  1. Jun 18, 2013 #1
    1. The problem statement, all variables and given/known data
    Question: Calculate the wavelength in mm of the most intensive microwaves

    Question before: State the intensity of the most intensive microwaves detected
    Answer: 380 Units. (5 Waves per CM)
    [Read from a graph]



    2. Relevant equations

    None given.

    3. The attempt at a solution

    I have never attempted a question to calculate wavelength from intensity. After some quick research on the internet, information about photons etc which I had never come across before showed up. If anyone would like to explain, i'd be very grateful.
     
  2. jcsd
  3. Jun 18, 2013 #2

    PeterO

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    Homework Helper

    This sounds like a microwave equivalent of a common optics question.

    There is a formula of calculating the energy associated with a photon of Red light, and a photon of blue light (one is bigger than the other).

    Thus if you have a 6W red light and a 6W blue light (6 joules given off each second), then there will be different numbers of photons given off by each light.
    If one phonon has 0.5 J of energy, you need 12 per second, while if the other photon has 0.6 J of energy, you need only 10 per second.

    Perhaps that example/concept will help.
     
  4. Jun 19, 2013 #3
    I did more research into this and I found out that Wavelength=HC/E

    But i'm still stuck on getting the E (energy of a photon)

    So far I've got

    WL=1.99x10-25 J-m x E
     
  5. Jun 19, 2013 #4

    PeterO

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    Homework Helper

    In your original post you said the nswer to the previous question was
    Answer: 380 Units. (5 Waves per CM) which you got from a graph.

    Using the scale of that graph what is a "unit"?
     
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