Which materials conduct magnetic lines of force very well?

• A. Diamagnetic
• B. Paramagnetic
• C. Ferromagnetic
• D. Superparamagnetic

Answer: (C)

The main idea here is magnetic permeability—the ability of a material to channel magnetic flux lines. Ferromagnetic materials have many magnetic domains that can align with an external magnetic field, producing a large net magnetization and a very high permeability. When the field is applied, these domains align and grow in the direction of the field, creating a low-reluctance path for the magnetic flux. That means magnetic lines of force can pass through and stay concentrated inside the material, effectively conducting them very well. Diamagnetic substances generate an induced field opposite to the external field and only weakly repel lines, so they do not guide flux effectively. Paramagnetic materials are only weakly attracted to fields and have low permeability, offering little guidance for flux compared with ferromagnets. Superparamagnetic materials respond strongly to a field only while the field is present and don’t retain magnetization, so they don’t provide the stable, low-reluctance path that ferromagnets do.