Physics Theory : Magnets
Magnetic poles are the points (N for north and S for south) slightly within the ends of a magnet where most of its magnetic power (influence) appears to be concentrated.
Magnetic axis is defined as the imaginary line NS which passes through the magnetic north and south poles of any bar magnet.
Length of magnet is defined as the distance between one of the magnetic poles and the centre of the magnet (ON = OS = L).
Effective length is defined as the distance between the magnetic north pole and the magnetic south pole of a bar magnet (NS = 2L).
Magnetic equator is defined as the imaginary line WE perpendicular to the magnetic axis NS and bisecting the effective length of the magnet.
Magnetic meridian is defined as the imaginary vertical plane passing through the magnetic axis NS of a freely suspended bar magnet.
Equatorial meridian is defined as the imaginary vertical plane passing through the magnetic equator WE of a freely suspended bar magnet.
Magnetic substances (or magnetic materials) are those which can be influenced by a magnet.
Soft iron can be easily and highly magnetized.
Steel cannot be magnetized very highly.
Repulsion is the surest test for magnetism.
Magnetism can act through non-magnetic materials.
Loss of magnetism occurs if magnets are strongly heated, or even knocked or hammered.