What is the wavelength of a photon emitted when an electron in hydrogen goes from the n = 4 state to n = 1 ?

try using the reference table if u have one right now.... find the difference of the energy in eV i think, then plug it into one of those formulas where E is equal to some sort of equation ((i forget, but i know theres like 3 of them, and includes E=mc^2 and E equals to something with frequency and planck's constant...)) or other than that, use the front page where a whole lot of wht is wht and the one with the frequency formulas, like v = f ( w ) ((w is for wavelength, cuz i cant type tht greek symbol "landa"...))

i hope this helps a bit...