Which of the following best explains why the relative permeability of a ferromagnetic…
PHYSICS · Single correct · CBSE · Physics · Magnetism and Matter · Magnetism and Matter
Problem
Which of the following best explains why the relative permeability μr of a ferromagnetic material typically drops sharply when the material is heated above its Curie temperature?
(a) Above the Curie temperature the aligned domains are forced into an antiferromagnetic arrangement that cancels the magnetization, so μr falls sharply.
(b) Thermal energy disrupts the alignment of magnetic domains, greatly reducing the net magnetization created by a given field.
(c) Heating excites many valence electrons to higher orbitals, leaving fewer unpaired electrons to contribute to magnetism, thus lowering μr.
(d) Greater thermal motion increases electron–lattice collisions, raising resistivity; with less current the material cannot sustain a strong internal magnetic field, so μr decreases.