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Saha equation to determine fraction of hydrogen atoms ionised

  1. Apr 8, 2013 #1
    So i have a homework question which i cant figure out.
    Use the saha equation to determine the fraction of hydrogen atoms that are ionised at the centre of the sun (N_II/N_tot)
    number density n=6.1x10^31 m^-3
    m = mass of electron

    the saha equation is
    N_(i+1)/Ni = 2*Z_(i+1)/n*Z_i * (2π*m*kT/h^2)^(3/2) * exp(-χ_i/kT)

    i get that Z_I=2 and Z_II=1 because we are assuming most of the hydrogen is in the ground state(or is that what im doing wrong)? Ive also tried changing units from J to eV but that doesnt seem to be doing anything.

    i think at the end of this im meant to get a fraction or percentage, but i keep getting stupid numbers like to the power of -34. can someone tell me what im doing wrong?
  2. jcsd
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