What is the wavelength of a photon (in nm) of light emitted resulting from an electron in a hydrogen atom
undergoing a transition from a n=5 to and n=1 electronic orbital? What is the energy in Joules of an Einstein of these photons (Avogadro's number of photons)? What would be the wavelength (nm) emitted if this were a Helium +1 ion (He+1) instead of a H atom