Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted

Similar Threads - Saha equation determine Date
A Lane-Emden equation Mar 7, 2018
B The Moon's inclination to Earth's equator Feb 2, 2018
I Proving equation for duration of transit Jul 31, 2017
Saha equation partition function for Argon? Apr 19, 2015