Electrical Engineering ⇒ Topic : Modern View about Magnetism

Modern View about Magnetism

According to modern view, the magnetic properties of a substance are attributed to the motions of electrons (orbital and spin) in the atoms. We know that an atom consists of central nucleus with electrons revolving around the nucleus in different orbits. This motion of electrons is called orbital motion [See Fig. a (i)]. The electrons also rotate around their own axis. This motion of electrons is called spin motion [See Fig. a (ii)].Due to these two motions, each atom is equivalent to a current loop i.e. each atom behaves as a magnetic dipole.

                                                               figure (a)

• In the unmagnetised substances, the magnetic dipoles are randomly oriented so that magnetic fields mutually cancel. When the substance is magnetised, the magnetic dipoles are aligned in the same direction. Hence the substance shows net magnetism.
• Since the revolving and spinning electrons in each atom cause magnetism, no substance is non-magnetic.
• It is important to note that spinning motion of electrons in particular is responsible for magnetism of a substance