If 15eV photon interacts with a Hydrogen atom at groundstate [-13.6eV], and all 15eV is transfered to the atom. How would the KE of the ejected electron be found? and what is the de Broglie wavelength of the electron? For the Kinetic Energy, i said 15eV = KE + 13.6eV, KE = 1.4eV for the wavelength, i have no clue. any help?