It is shown that albeit the fundamental character of the induction field <img src="http:/img/fbpe/rbef/v23n2/sbgvec.gif" align="absmiddle">, it is the magnetic field <img src="http:/img/fbpe/rbef/v23n2/shgvec.gif" align="absmiddle"> the magnetizing field in para and ferromagnetism, phenomena depending on the orientation of magnetic dipoles. However, in diamagnetism, whose extreme case occurs in superconducting materials, the inducting field is <img src="http:/img/fbpe/rbef/v23n2/sbgvec.gif" align="absmiddle">. The relations <img src="http:/img/fbpe/rbef/v23n2/sbgvec.gif" align="absmiddle"> = <img src="http:/img/fbpe/rbef/v23n2/shgvec.gif" align="absmiddle"> + 4pi<img src="http:/img/fbpe/rbef/v23n2/smgvec.gif" align="absmiddle"> e <img src="http:/img/fbpe/rbef/v23n2/sdgvec.gif" align="absmiddle"> = <img src="http:/img/fbpe/rbef/v23n2/segvec.gif" align="absmiddle"> + 4pi<img src="http:/img/fbpe/rbef/v23n2/spgvec.gif" align="absmiddle"> are obtained and the differences between them stressed. The demagnetization effect and the status of the Amperian currents are discussed.
