Write three points of difference between para-, dia- and ferro-magnetic materials, giving one example for each.
Solution
Diamagnetic materials are weakly repelled by a magnet, have small negative susceptibility and relative permeability slightly less than 1, and the effect is nearly temperature-independent - example: bismuth.
Paramagnetic materials are weakly attracted, have small positive susceptibility and relative permeability slightly greater than 1, and the susceptibility decreases with temperature (Curie law) - example: aluminium.
Ferromagnetic materials are strongly attracted, have very large positive susceptibility and relative permeability, retain magnetisation (hysteresis) and become paramagnetic above the Curie temperature - example: iron.
Paramagnetic materials are weakly attracted, have small positive susceptibility and relative permeability slightly greater than 1, and the susceptibility decreases with temperature (Curie law) - example: aluminium.
Ferromagnetic materials are strongly attracted, have very large positive susceptibility and relative permeability, retain magnetisation (hysteresis) and become paramagnetic above the Curie temperature - example: iron.
CBSE Class 12 Board · 2019 · Subjective