Identify the incorrect statement from the following.

Options

A. The susceptibility of a diamagnetic material is a positive quantity.
B. Paramagnetic materials obey Curis's law.
C. Ferromagnetic materials have permanent magnetic domains.
D. In soft ferromagnetic material, the magnetisation disappear on removeal of the external field.

Answer

A

Explanation

Susceptibility of a diamagnetic material is a negative quantity `(chilt0)` while paramagnetic, ferromagnetic and superparamagnetic material have positive susceptibility `(chigt0)`, hence it is incorrect statement.
Paramagnetic materials obey Curie's law. Ferromagnetic materials have perimanent magnetic domains and each domain contains near about `10^(17)` atoms,
Magnetisation of soft ferromagnetic substance disappera easily after removel of external magnetic field.
So, among the given statement statement (a) is incorrect.
Hence, the correct option is (a).