9. Consider a quantum particle of mass m, moving under the influence of a force given by F = mw^2r, where w is a constant, and r is the radial distance from the origin. The corresponding potential energy of the particle is given by:
(a) Assume that the particle moves around the origin in circular orbits. Show how Bohr's quantization condition arises from trying to fit de Broglie waves of the particle around a circle. [2]
(b) Using Bohr's quantization condition, find an expression for the allowed radii rn for the particle's orbits. Also, find the corresponding orbital speed vn for each orbit. [4]
(c) What is the kinetic energy K and potential energy U of the particle when it is in the orbit with quantum number n? What is its total energy En? [4]
(d) Hence, write down the analogue of the Rydberg formula. [2]
[Remark: This is a simplified model of the so-called harmonic oscillator.]