It states
that the angular momentum of the electron orbiting around
the nucleus is quantised (that is, Ln = nh/2p; n  = 1, 2, 3 …) Why should the angular momentum have only those values
that are integral multiples of h/2p The French physicist Louis
de Broglie explained this puzzle in 1923, ten years after Bohr
proposed his model We studied, in Chapter 11, about the de Broglie’s
hypothesis that material particles, such as electrons, also
have a wave nature