Using Balmer's Series equation: 1/wavelength = R[1/2^2 - 1/n^2] where n = 3,4,5...
What number should be in place of the 2 in the denominator for a spectrum to be emitted in the infrared region?
((There was a sample problem for a red line in the hydrogen spectrum: 1/wavelength = (1.097 x 10^7m^-1)[1/4 - 1/9]. This totalled 656.3 nm, but I cannot figure out how to do this on my calculator??))