The problem statement, all variables and given/known data Calculate the threshold ionization intensity for hydrogen gas. The attempt at a solution The way I tried to work it out was to use the field intensity of air which breaks down at, 3x10^6V/m. The ionization potential of oxygen is 13.618ev, 14.534ev for nitrogen and 13.598ev for hydrogen. So I was thinking that the ionization potential of air would be around the same for hydrogen. Am I on the right track with this?