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प्रश्न
Assume that each iron atom has a permanent magnetic moment equal to 2 Bohr magnetons (1 Bohr magneton equals 9.27 × 10−24 A m2). The density of atoms in iron is 8.52 × 1028 atoms m−3. (a) Find the maximum magnetisation I in a long cylinder of iron (b) Find the maximum magnetic field B on the axis inside the cylinder.
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उत्तर
Given:-
No of atoms per unit volume, f = 8.52 × 1028 atoms/m3
Magnetisation per atom, M = 2 × 9.27 × 10−24 A-m2
(a) Intensity of magnetisation, \[I = \frac{M}{V}\]
⇒ I = 2 × 9.27 × 10−24 × 8.52 × 1028
⇒ I = 1.58 × 106 A/m
(b) For maximum magnetisation ,the magnetising field will be equal to the intensity of magnetisation.
So, I = H
Magnetic field (B) will be,
B = 4π × 10−7 × 1.58 × 106
⇒ B ≈ 19.8 × 10−1 = 2.0 T
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