Practice portal › Magnetism and Matter › Magnetisation and Magnetic Materials
Asked in GUJCET 2008 · Magnetisation, intensity and susceptibility
Given: N=2.0×10²⁴ dipoles, each of moment m=1.5×10⁻²³ A m².
Idea: saturation means every molecular dipole has been turned to point the same way, so the individual moments simply add.
Total moment =Nm=(2.0×10²⁴)(1.5×10⁻²³).
Mantissas: 2.0×1.5=3.0. Powers of ten: 10²⁴×10⁻²³=10¹.
So Nm=3.0×10¹=30 A m².
Note what the options measure: they are in A m², so what is wanted is the saturated dipole moment of the whole specimen, not the magnetisation M (moment per unit volume, unit A m⁻¹) -- no volume is given, so it could not be found anyway.
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