To calculate the frequency of the magnetic field, we use the following experiment: two annular magnets with identical characteristics are placed facing each other by the same poles vertically. The upper magnet is in equilibrium thanks to the interactions between the force of its weight and the magnetic force of the lower magnet. Therefore, the gravitational potential energy of the upper magnet must be equal to the magnetic energy of the lower magnet. Then we measure the distance between the two magnets and introduce two formulae for energy and frequency of the magnets.