State Bohr’s postulate for the ‘permitted orbits’ for the electron in a hydrogen atom. Use this postulate to prove that the circumference of the nth permitted orbit for the electron can ‘contain’ exactly n wave lengths of the de Broglie wavelength associated with the electron in that orbit.

According to bohrs second postulate, the electron revolve around the nucleus  only in  those  orbits  for which the angular momentum is some integral multiple of h/2π, where he is planks constant.      Thus the angular momentum of orbiting electrons is L = nh/2π.                                                                        Circumference of electron in nth orbit = n×debrogli wavelength associated with electron