Answer Happy

In the derivation of his equation, Johannes Rydberg realized that the second n value must be greater than the first. Why? Because the equation was aiming to show that the wavelength of light emitted would increase as the difference between n values increased. Because Rydberg knew that emission of light meant that the electron was moving from a high value of n to a low value of n. Because the energy levels for the electron are numbered in ascending order, so they need to follow ascending order in the equation. By imposing this condition, the calculated wavelength is guaranteed to have a positive value.