As the electron in the atom makes a transition between two stationary states ( neither of which shows a dipole field ), it enters a transition state which does have a dipole field, and which acts like a small electric dipole, and this dipole oscillates at a characteristic frequency.

As the electron in the atom makes a transition between two stationary states ( neither of which shows a dipole field ), it enters a transition state which does have a dipole field, and which acts like a small electric dipole, and this dipole oscillates at a characteristic frequency.

0.004 seconds.