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Magnetic properties of Matters

Hi guys, This is Maxaniverse 
I'm here to tell you about the magnetic properties of matter

Magnetic properties

1) The magnetic intensity or magnetising force {H} :



B=μ。nI

B=μ。H

when a specimen of the material is placed in a uniform magnetic field then it experiences a force called magnetic intensity, denoted by  H.

H=nI
B=μ。H
H=B/μ。



2) The intensity of the magnetic field or magnetization {I}:




The degree or extent up to which a material is magnetised when placed in a uniform magnetic field

It is measured by dipole moment per unit volume



I=M/V

I=m x 2l/A x 2l
I=m/A    where small  m is pole strength of the magnet



SI unit: A/m


3) Relative permeability:

The ratio of magnetic field lines passing through a given area of a medium is to the total number of magnetic field lines passing through the same area of air or vacuum

        μᵣ =μₘ/μ。

SI Unit: μᵣ is dimensionless  and hence unitless


4) Magnetic susceptibility :

It describes how easily  a magnetic material can be magnetised when placed in a magnetic field
 Xₘ= Intensity of magnetic field(I)/magnetising force (H)

Xₘ=I/H

The relation between relative permeability  with magnetic susceptibility:

μᵣ=1+xₘ     (M.K.S)
μᵣ= 1 +4xₘ (C.G.S)

Classification of materials:

1. Diamagnetic 
2. paramagnetic 
3. ferromagnetic




Diamagnetic materials:


Dmat. are those in which individual atom or ions possess no net magnetic dipole moment

 Properties :
  1.   When these material are placed in the uniform magnetic field, they do not get magnetised at all.
  2.  These materials repel the magnetic field
  3.   Since the magnetic field line does not prefer to pass through these materials,           therefore their relative permeability is zero {μᵣ=o}
  4.  Magnetic susceptibility of a diamagnetic material is -1
                μᵣ=1+xₘ
                0=1+xₘ
                xₘ=-1
      5.  When these materials are suspended in a uniform magnetic field, they can align                                    themselves perpendicular to the direction of the magnetic field

    6. Diamagnetic materials remain unaffected by the change in temperature

 Paramagnetic material:

 Pmat is those materials in which individual atom or ions posses some net, magnetic dipole moment.  when these materials are placed in a uniform magnetic field, they get magnetised along the direction of the magnetic field.

Properties:

 Since magney=tic filed lines are attracted by paramagnetic materials, therefore their permeability and relative permeability is higher uᵣ>1

2. μᵣ>1;
therefore   μ。=1+xₘ
xₘ=+ve

x=c/ T, where c is curies constant
 magnetic susceptibility of the paramagnetic material is +ve

3. When these materials are placed in a non- uniform magnetic field, then they move from weaker to the stronger magnetic field

4. When paramagnetic materials are suspended in a uniform magnetic field, then they align themselves along the direction of the magnetic field


5. When the temperature is increased paramagnetic materials start losing their magnetic properties  and at curies temperature, these materials lost all the magnetic properties


 Ferromagnetic materials:

 Fmat are those materials in which individual atom or ions posses some net magnetic dipole moment greater then paramagnetic materials and when these materials are placed in a uniform magnetic field they get magnetised strongly in the direction of the magnetic field
e.g iron, steel, nickel, cobalt, and their alloys

Properties:

 All the properties of ferromagnetic materials are the same as that of paramagnetic material but intensified.

μₘ is greater
μᵣ=μₘ/μ。
μᵣ is greater
μᵣ= 1 +xₘ
μᵣ>>1, therefore, xₘ>1

when the temperature of the ferromagnetic material increased their magnetic susceptibility start decreases and at the Curie temperature. ferromagnetic material lost all their magnetic properties


 Curie temperature for some material at which they losses their magnetic properties
iron = 1043K
cobalt=1404.2K




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