Revision: Class 12 >> Magnetism NEET (UG) Magnetism

An imaginary line (XY) passing through the magnetic north pole and magnetic south pole of a bar magnet is called its magnetic axis.

The angle between the horizontal and earth’s magnetic field is known as the angle of dip.

It is a piece of lodestone, which is a black iron oxide (Fe₃ O₄) called magnetite. The word lodestone means a leading stone.

The region around a magnet where its magnetic force can be experienced is called the magnetic field.

Pieces of iron and other magnetic materials which can be made to acquire the properties of natural magnets are called artificial magnets.

lt is a solenoid with a soft iron core placed inside it. When current is passed through the solenoid, the soft iron core becomes a temporary magnet.

The distance (NS) between the north pole and south pole of a magnet is called the length or effective length of the magnet.

The substances which have the property of attracting small pieces of iron, nickel, cobalt, etc, are called magnets, and this property of attraction is called magnetism.

An imaginary line (PQ) bisecting the effective length of a magnet is called the magnetic equator of the magnet.

The magnetic dipole moment is defined as the product of its pole strength and magnetic length.

`vec"P" = "q"_"m"vec"d"`

The temperature above which a ferromagnetic substance becomes paramagnetic is called curie temperature. 

The ratio of magnetic moment to the volume of the material is called magnetization.

The ratio of the strength of the magnetizing field to the permeability of free space is called magnetic intensity. 

Tangent law states that, if a magnetic field ‘B’ is applied at right angles to the horizontal component of the earth's field B_H, the needle comes to equilibrium at an angle ‘$\theta ’$ to the magnetic meridian such that, tan θ = `B/B_H`.