Flexi Says: Atomic emission spectra are produced when excited electrons return to ground state. The emitted light corresponds to energies of the specific electrons. To find the wavelength of the emitted light, first find the energy difference from the excitation state to the ground state. The energy of an electron in a given energy level of hydrogen is calculated by En=(−2.17×10−18 J)(1/n2). Subtract the energy of the electron in the ground state from the energy of the electron in the excitation state to determine the energy lost by the electron, which will equal the energy of the emitted photon. You can find the wavelength of the photon using the equation λ = hc/E, where h is Planck's constant (6.626 × 10-34 J • s) and c is the speed of light (3.00 × 108 m/s).