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Photons per second from a radio transmitter

  1. May 3, 2008 #1
    1. The problem statement, all variables and given/known data

    A radio transmitter radiates at the power of 10 kW at a wavelength of 100 m. How many photons does it emit per second?

    2. Relevant equations

    [tex]E=hv[/tex], and some other equations of beginnings of wave mechanics.

    3. The attempt at a solution

    I had no idea where to start.Please do not give me the whole solution, but, rather, a hint (big hints) so that I understand how to do problems like that myself. Oh btw, I am completely beginner in WM, so go easy.

    Edit: I think I started to figure out some things.

    If we know the wavelength, we can find out the energy of the photon, and then calculate how many photons are there to make up the 10 kW. Is that right? And if it is, how exactly would you know the units of photon's energy?
    Last edited: May 3, 2008
  2. jcsd
  3. May 3, 2008 #2


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    Staff Emeritus
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    Homework Helper

    You have the "Joules/sec" for the transmitter. Also, you're aware of how to calculate "Joules/photon" (Joules per photon).

    How would you combine the two quantities quoted in the above paragraph, in order to get something with units of "Photons/sec", i.e photons per second?
  4. May 3, 2008 #3
    ohhh =D

    yessir clear now
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