how do i calculate the wavelength of light emitted by a hydrogen atom?
Do you know the shells involved in the electron movement. If so, then
E = 3.18 x 10^18 J [(1/n12) - (1/n22)]
That 3.18 x 10^18 should be
2.18 x 10^-18
The answer is in units of Joules/photon. That is for one transition of one electron.