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Finding energy from a wave

  1. Aug 30, 2009 #1
    1. The problem statement, all variables and given/known data
    I need to find the energy transfered per unit time from a microwave oven, and the only information I have is:

    Wavelength = .122m
    Peak Magnetic Field of microwaves = 1.3*10^-5 T


    2. Relevant equations
    c=f*lambda
    I = (c*B^2)/(permeability of free space) = EB / (permeability of free space)


    3. The attempt at a solution
    My problem is I need either "c" or "f" in c=f(lambda) OR the electric field..... I think? I'm not quite sure what to do.
     
  2. jcsd
  3. Aug 30, 2009 #2

    Redbelly98

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    You can find I from the given B. Two more things to think about:

    1. Using the peak B given will result in the peak of I. What will be the average of I?

    2. How does I relate to power?
     
  4. Aug 30, 2009 #3
    Ok, but I run into the same problems again. I have neither c nor E so Im stuck with 3 unknowns.
     
  5. Aug 30, 2009 #4

    Redbelly98

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    But you do have c. Think about it ... what is c?
     
  6. Aug 30, 2009 #5
    OH! I'm an idiot. c is just the speed of light isnt it? so 2.99 x 10^8 m/s
     
  7. Aug 30, 2009 #6

    Redbelly98

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    Yes.
     
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