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Homework Help: Rutherford scattering thin gold foil

  1. Oct 21, 2013 #1
    1. The problem statement, all variables and given/known data
    The fraction of 6.0 MeV protons scattered by a thin gold foil, of density 19.3 g/cm^3, from the incident beam into a region where scattering angles exceed 60° is equal to 2.0(10^-5). Calculate the thickness of the gold foil.

    2. Relevant equations


    3. The attempt at a solution
    I solved for t, giving

    For Mv^2, I used 2*6 MeV, converted to joules. For ρ, I used the number of molecules in one cubic meter of gold, which is 98,000. For theta I used 60°. The ratio N/I is given: 2(10^-5). I used 8.988(10^9) m/F for 1/4piε. Z=79, and z=1, e=1.602(10^-9) coulombs.

    I plugged in all known values and got 4.17(10^17). Obviously wrong, but I don't understand why I am so off. I check the units and everything. Anybody see what's wrong?
    Last edited: Oct 21, 2013
  2. jcsd
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