Magnetization and Magnetic Field

Magnetization and Magnetic Field

Introduction :In previous topic we have studied about orbital magnetic dipole moment  and the net magnetic dipole moment leads to magnetic property in a substances. Let us focus on new term magnetization which is related to magnetic property of a substance.

Magnetization(Mz) is defined as net magnetic dipole moment per unit volume.

Magnetization is a vector quantity  and it's SI unit A/m.

Dimension :[ L^-1 M⁰ T⁰ I¹] 

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Let us study magnetization of a ferromagnetic material like Iron. Let us consider a solenoid having n turns per unit length and carries a current I. 

thus the magnetic field inside the solenoid is given by

B₀ = μ₀nI 

B₀ = μ₀H -----(A) (nI = H)

However, if any conductor is placed inside the solenoid , the magnetic field inside is larger than B₀ and it is written as,

B = B₀  + B_M -----(B)

From theory it is found that B_M is directly proportional to Magnetization M_z 

B_M ∝ M_z

B_M = μ₀ M_z -----(C)

Putting (A) and (C) in (B) we get,

B = μ₀H + μ₀ M_z 

B = μ₀(H + M_z) ----(D)

Equation (D) gives total Magnetic field or Magnetic Intensity 

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 Mathematically, magnetization and magnetic Intensity is related as 

M_z ∝ H

M_z= χ H ----(E)

where χ  is called a magnetic Susceptibility.

From (D) and (E)

B = μ₀(H + χ H) 

B = μ₀(1 + χ )H

B = μ₀μ_rH    

  ---(μ_r =1 + χ ) is a dimensionless quantity called as relative magnetic permeability.

B = μH   -----(μ = μ₀μ_r)

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_{│<<<Magnetic Dipole Moment  of an electron>│} 

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