## Relative magnetic permeability

Relative magnetic permeability is defined as the ratio of permeability of medium (μ) to the permeability of free space (μ0)

μr = μ/μ0

or                                 μr = B/H/(B0/H)

or                                 μr = B / B0

is permeability of free space.

## Magnetic permeability

Magnetic permeability is defined as the degree to which the magnetic lines of force can penetrate or permeate the material. It can also be defined as the ability of the material to permit the passage of magnetic lines of force through it.

As the magnetic induction is proportional to the magnetising field

B proportional H

or                     B = μH

where μ is called the permeability of the medium (material)

## Intensity of magnetisation

It represents the extent to which a specimen is magnetised when placed in a magnetising field.

Or in other words the  intensity of magnetisation of a magnetic material is defined as the magnetic moment per unit volume of the material.

M = Magnetic moment/volume = μM / V                            …1

Let       a = Uniform area of cross-section of the magnetised specimen.

l = magnetic length of the specimen.

m = strength of each pole of the specimen,

As                    μm = ml

and                   V = al

then equation (1) becomes

M = m x 2l / a x 2l

or         M = m/a

thus intensity of magnetisation of  a  magnetic material is also defined as the pole strength per unit area of cross-section of the material.

Unit :    M= magnetic moment / Volume

M= Amp.metre2 / metre3 = Am -1

These are S.I unit of M

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## Magnetic Intensity

Magnetic intensity is same as magnetizing force.

Therefore, it is also defined as the degree to which a magnetic field can magnetise a material is expressed in terms of magnetizing force.

Consider a toroidal solenoid with n turns per unit length carrying a current I. The magnetic induction of the field produced will be Continue reading “Magnetic Intensity”

## Magnetising Force

The degree to which a magnetic field can magnetise a material is expressed in terms of magnetizing force.

Consider a toroidal solenoid with n turns per unit length carrying a current I. The magnetic induction of the field produced will be Continue reading “Magnetising Force”

## Magnetic flux density

Magnetic flux density is also known as magnetic induction.

When a magnetic material is placed in an external magnetic field then material gets magnetized. Such magnetism produced in the material is called induced magnetism and the phenomenon is called is called magnetic induction

It is also defined as the number of magnetic lines of force inside a magnetized material crossing unit area normal to their direction.

Its S.I. units are weber per square meter.

## Magnetic Induction

When a magnetic material is placed in an external magnetic field then material gets magnetized. Such magnetism produced in the material is called induced magnetism and the phenomenon is called is called magnetic induction

It is also defined as the number of magnetic lines of force inside a magnetized material crossing unit area normal to their direction.

It is given by                 B = Φ/A

Its S.I. units are weber per square meter.

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## Magnetic Flux

The Magnetic flux Φ through any surface held in a magnetic field b is measured by the total number of magnetic lines of force crossing the surface

where d S = small area element through which line is passing.

Units

The S.I. unit of magnetic flux is weber (Wb). One weber is the amount of magnetic flux crossing over an area of 1 metre2 held normal to a uniform magnetic field of one tesla.

Thus                           1 weber = 1 tesla x 1 m2

The c.g.s. unit of Φ is maxwell (Mx),

where             1 weber = 108 maxwell

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## Magnetic dipole moment

Magnetic dipole moment is defined as the product of pole strength and the distance between the two poles.

Let a → distance between the poles also called magnetic length,

and m → strength of each pole.

Thus, magnetic dipole moment, pm is given as

pm = ma

pm is vector quantity directed from south to north pole.

S.I units of pm are joule/tesla or ampere metre2.