A neutral Helium atom with charge Z=2 has been excited by an external photon, so that one of the ground state electrons has been ejected, and the other electron excited to the N=5 shell. The ionized Helium atom can now be a source of laser beam of wavelengths, from N= 5 shell to n=2 shell .
What is the wavelength of the laser beam ? Recall that the ground state energy of a Hydrogen atom is 13.6 eV. hc = 1.241 x 10-6 eV-m.
Give your answer in nm to 0 decimal place.