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Homework Help: Photoelectric effect and frequency

  1. Sep 28, 2008 #1
    1. The problem statement, all variables and given/known data

    the wavelengths of visible light range from about 380 nm to 750 nm. what is the range of photon energies (in eV) in visible light? a typical fm radio station's broadcast frequency is about 100Mhz. what is the energy of an FM photon of the frequency?

    2. Relevant equations
    eVo=hf-(phi)
    phi=hfo
    i don't know how to get fo which is the threshold frequency. thats the only part im stuck with


    3. The attempt at a solution
    i don't know how to get fo which is the threshold frequency.
     
  2. jcsd
  3. Sep 28, 2008 #2

    gabbagabbahey

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    The energy of a photon of frequency [itex]f[/itex] is given by [itex]E=hf[/itex].

    [itex]eV_0=hf-hf_0[/itex] allows you to determine the difference in electric potential necessary to make electrons in a material with a threshold frequency [itex]f_0[/itex] to emit photons of frequency [itex]f[/itex]. This equation is useless to you here. You are simply asked to determine the energies of photons of a given wavelength or frequency.
     
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