Correct Answer - Option 2 : Greater
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
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.
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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.
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Relation between M and H:
⇒ M = χH
Where χ is the dimensionless quantity called magnetic susceptibility.
EXPLAINATION:
- When a paramagnetic substance is cooled, the thermal agitation of its dipoles gets reduced.
- So when the same magnetic field is applied at the lower temperature, due to reduced random motion of the dipoles, the dipoles face less disruption. Hence they shall have a better alignment and hence greater magnetization. Hence option 2) is correct.
