Magnetic materials

Magnetic materials

Introduction : The word magnet, was first used for iron ore magnetite ( Fe₃O₄) which was found in magnesia. The natural magnet which is found in nature is called as Loadstone. It has two important properties viz. directive and attractive property. If a magnet is suspended freely using a string , it comes to rest in north south direction which describe the descriptive property . If the loadstone is dipped in iron fillings, they get attracted to the loadstone which tells us about attractive property. We will discuss more about it in details.

Origin of magnetism

Origin of magnetism

We have already studied that, flowing charges in  a conductor  produces magnetic field. Thus magnetism is cause of moving charges. In case of an atom, negatively charged (Electron)  revolve around the nucleus which is similar to current flowing in a circular loop called as "current loop". This circular loop of the electron constitutes orbital magnetic moment . While revolving in a circular orbit electron spins about it's own axis, constituting spin magnetic moment. Thus the total magnetic moment (M) of any atom is vector sum of orbital magnetic moment and spin magnetic moment.

Generally in  any substance, atomic magnetic moment are in random direction  such that net magnetic moment is zero. thus such substance do not show magnetic property.

If any substance has it's atomic magnetic moment in a specific direction, then the magnetic moment is not zero, thus such substance shows magnetic properties and are called as magnetic material.

 _{│Magnetic Dipole moment of an electron>>>│} 

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