Magnetism And Matter

Magnetic permeability is a measure of conduction of magnetic lines of force through it. Magnetic permeability is denned as the ratio of the magnetic induction inside the magnetised substance to the magnetic intensity of the magnetising field, that is Permeability of diamagnetic substances is slightly less than unity, permeability of paramagnetic substances is slightly greater than unity, and permeability of ferromagnetic substances is many times that of air.

Let be the magnetic field at some point. H and V be the horizontal and vertical components of and is the actual angle of dip at the same place.

and

or ...(i)
In a vertical plane at from the magnetic meridian, the horizontal component is

While vertical component is still V. Therefore, apparent dip will be given by
...(ii)
Dividing E(i) by E(ii),we have


or

Ferromagnetic materials used in a transformer must have high permeability and low hysterisis loss.

The magnetisation

As temperature is increased the magnetisation decreases.

Answer (d)

The magnet in a magnetic field experiences a torque which rotates the magnet to a position in [which the axis of the magnet is parallel to the field.

where, M is magnetic dipole moment, B the magnetic field and the angle between the two.
Given, .


Dividing E (i) by E (ii) , we ge

The angle of dip at a place on the earth gives the direction of the earth's magnetic field.

Torque


or