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 magnetization I in a long cylinder of iron.
(b) Find the maximum magnetic field B on the axis inside the cylinder.
Given:
Density of atoms in iron=8.52× 1028 atoms m-3
Permanent magnetic moment (M) of each atom =2× 9.27× 10-24Am-2
Intensity of magnetization(I) is given by the formula
…(i)
Where
M=magnetic moment
V=volume
Considering volume to be 1m3
No. of atoms in this volume =8.52× 1028
Therefore, total magnetic moment=8.52× 1028× 2×9.27× 10-24Am-2
Using eqn.(i) we get
Therefore, maximum magnetization is 1.58× 10-6Am-1
The net magnetic field is given by formula
Where
I=magnetization intensity
H=magnetic field intensity
We need to find the maximum magnetic field on the axis of cylinder.
Magnetizing field intensity (H) in this case =0
Therefore
Putting the values of I and μ we get
maximum magnetic field B on the axis inside the cylinder is 2T