The amount of energy needed to reverse the spin of the electron is equivalent to a photon at the frequency of hertz ( Hz ) } }, which corresponds to the 21 cm line in hydrogen spectrum.
12.
"' Willis Eugene Lamb Jr . "'( July 12, 1913 May 15, 2008 ) was an American physicist who won the Nobel Prize in Physics in 1955 " for his discoveries concerning the fine structure of the hydrogen spectrum . " The Nobel Committee that year awarded half the prize to Lamb and the other half to Polykarp Kusch, who won " for his precision determination of the magnetic moment of the electron . " Lamb was able to determine precisely a surprising shift in electron energies in a hydrogen atom ( see Lamb shift ).
