A nonrelativistic particle of charge e and mass m is bound by a linear, isotropic, restoring force with force constant mw²₀. Using (6.13) and (16.16) of Section 16.2, show that the energy and angular momentum of the particle both decrease exponentially from their initial values as e^–Γt, where Г = w²_0τ. Quantum mechanically, the mean excitation energy of an oscillator decays in exactly the same way because the total radiative transition probability for a state with quantum numbers n₀, I₀ is Γ(n₀, I₀) = n₀Г. The decay of the angular momentum approaches the classical law only for I₀ >> 1.