A glass tube is filled with hydrogen gas at a low pressure. An electric current is passed through the gas, causing it to emit light. This light is passed through a prism to separate the light into the bright, colored lines of hydrogen's visible spectrum. Each colored line corresponds to a particular wavelength of light. One of hydrogen's spectral lines is red light with a wavelength of 656 nanometers. Tubes filled other gases produce different bright line spectra that are characteristics of each kind of gas. These spectra have been observed and recorded. Explain in terms of electron energy states and energy changes, how hydrogen's bright line spectrum is produced.