What is Magnetism

Magnetism is the property of a material by which it gets attracted or repelled by a magnetic force in a magnetic field. It is produced due to two reasons:

First is by the inherent existing property of particles in a material such as magnets.

Secondly by the moving charged particles in which magnetism is induced.

All those objects which possess magnetism have a magnetic field associated with them. A magnetic field is the region around the object, in which the object attracts or repels other magnetic material in that region. Magnetic field contains imaginary lines of force known as magnetic field lines. Each magnetic object has a north (N) pole and a south-pole (S) end. The magnetic lines of force emerge out of the north pole of the object and goes into the object at south - pole. These lines of force are perpendicular at the surface of the object. Also the magnetic field lines are continuous lines.

Magnetic Fields are not only associated with the magnets but also with the conductors which carry electric current through them. The moving charged particles inside the conductor induce magnetism in it thereby developing magnetic field around them. The movement of the particles can be a spin, transnational motion etc like spin of a proton or translation of electrons in a current carrying conductor.

The Magnetic Fields of the magnetic objects creates a magnetic force on other bodies with magnetic field. This force is the property known as magnetism  The magnetic force of two objects is attractive if the objects are facing opposite poles (N-S or S-N) and it is repulsive if they face same magnetic poles (S-S or N-N).

Magnetic field applies a force on a charged particle which is passing through it. The force occurs in the direction perpendicular to the direction of movement of charge and that of the magnetic field. This applied force is known as Lorentz force. Lorentz force is also applied in a current carrying wire as the wire contains large number of charged particles (electrons, protons) in it.

The amount of magnetic field or magnetic field line that passes through a surface area is known as 

Magnetic Flux (φ) which varies with the surface area of the body, magnetic field (B) and its alignment with the surface area (A). Magnetic flux with a given strength of magnetic field and surface area will be maximum if the magnetic field lines are perpendicular to the surface.

φ=(B.A)cosӨ

Ө is angle between magnetic field and normal to the surface.