Correct Answer - Option 2 : 2) and 3) only
CONCEPT:
Magnetization (M):
- It is defined as the magnetic moment per unit volume of the material.
- Mathematically it is written as,
\(⇒ M=\frac{ m_{net}}{V}=\frac{m\; × \;2l}{a\;\times \;2l}=\frac{m}{a}\)
Where mnet = the dipole moment of the specimen, V = volume of the material, m = strength of each pole of the specimen, 2l = magnetic length of the specimen, and a = uniform cross-section area of the specimen.
- SI unit of magnetization Am-1
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Magnetic intensity (H), of a material medium, can be described as the capability of the magnetic field to magnetize it.
\(⇒ H=\frac{B_{0}}{μ_{0}}\)
Where B0 is the applied magnetic field, μ0 is the permeability of free space.
Magnetic field strength:
- Consider a solenoid carrying n turns per unit length and carrying current I. The magnetic field strength in the interior of the solenoid, B0 = μ0nI.
- The net field in the interior of the solenoid,
⇒ B = B0 + Bm
Where Bm is the field contributed by magnetic core given by, Bm = μ0M
⇒ B = μ0(H + M)
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SI unit of magnetic field strength is weber/meter2 or Wb m-2.
Magnetic susceptibility (χm):
- It is the property of the substance which shows how easily a substance can be magnetized.
- It is defined as the ratio of the intensity of magnetization (M) in a substance to the magnetic intensity (H) applied to the substance, i.e. \(\chi = \frac{M}{H}\)
- It is a scalar quantity with no units and dimensions.
⇒ B = μ0(1 + χ)H = μ0μrH = μH
Where μr is the relative permeability of the substance and μ is the magnetic permeability of a material
Relative permeability of the substance:
- The ratio of magnetic permeability of a material (μ ) to the magnetic permeability of the free space (μ0).
⇒\(μ_{r}=\frac{μ}{μ_{0}} =1+\chi\)
EXPLAINATION:
- SI unit of magnetization is Am-1
- SI unit of permeability TmA-1 (Tesla meter/ ampere)
- SI unit of magnetic field Tesla (T).
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Susceptibility is a dimensionless quantity. Hence it has no unit.
Hence option 2) is correct.