The energy levels found by quantum mechanics of free electrons in a uniform magnetic field. These energy levels, named after the Soviet physicist Lev Davidovich Landau (1908–68), who analysed the problem in 1930, have discrete values, which are integer multiples of heB/m, where h is the Planck constant, e is the charge of the electron, m is the mass of the electron, and B is the magnetic flux density. Each Landau level is a highly degenerate level, with each level being filled by 2eB/h, where the factor 2 is due to the spin of the electron. The analysis of Landau levels can be extended to electrons described by Bloch’s theorem.