magnetic media;  Diamagnetic;  induced electric field;  orbital electronics;  magnetic moment;  Susceptibility

Starting from the basic law of electromagnetic induction, the effect of induced electric field on orbital electrons in magnetic medium atoms is discussed, and a clear explanation is given for the antimagnetic diamagnetism. According to the obtained formula, the magnetic susceptibility is estimated by taking the common antimagnetic copper as an example. This quantitative calculation results are in good agreement with the accepted values in the general physics literature in terms of orders of magnitude.