I have worked on this problem for about an hour, looked through the book lots of times, and honestly just don't know how to get it done. So I am here with all you fellow physicists for help! :) 1. The problem statement, all variables and given/known data X rays bombarding heavy atoms can be used to eject electrons from the 1s shell in atoms; indeed, this is the starting point for Moseley’s experiments. Estimate the maximum wavelength of pho- tons required to eject an electron from the 1s shell of copper, for which Z = 29. Planck’s constant is 6.63 × 10−34 J · s and the speed of light is 3 × 108 m/s2. Answer in units of nm. 2. Relevant equations here is what I have found: E=hc/lambda lambdamin=hc/Ko E=-(z)^2x13.6eV/n^2 These may seem like random equations, but honestly, these are all the ones I think that may be relevant. I can't figure out a starting point here at all. 3. The attempt at a solution I tried solving several times. I assume that since we are ejecting the electron from the 1S shell, it has very high energy since it's so close to the nucleus. I tried this -z^2x13.6eV/n^2=hc/lambda to solve for lambda, but I am stuck with what to do with the quantum number. Does ejecting the electron from 1s change the n from 1 to something else? Thanks Edit: What's weird is that the question also asks to "estimate" the max wavelength. Does that in any way change anything?