Question

Susceptibility of ferromagnetic materials is always:
1. Large and positive
2. Small and positive
3. Large and negative
4. Small and negative
5. None of the above

Answer 1

Correct Answer - Option 1 : Large and positive

Concept:

The magnitude of the internal polarization (J) divided by the strength of the external field (B) is called Magnetic susceptibility. 

It is denoted by the Greek letter chi (χ).

Based on magnetic property materials are of 4 types:

1. Diamagnetic
2. Paramagnetic
3. Superparamagnetic
4. Ferromagnetic

 

Explanation:

The susceptibility of ferromagnetic material is Large and positive. Ferromagnetic materials follow the Curie – Weiss law. When ferromagnetic substance heated above Curie temperature (T_c) 

\(i.e.\;χ \propto \frac{1}{{T - {T_C}}}\)

Below table shows χ for different materials:

Material	Magnetic Susceptibility	Examples
Diamagnetic	-10	Water, Most biological substances
Paramagnetic	+1	Molecular O2, Simple salts
Superparamagnetic	+5,000	Ferritin
Ferromagnetic	> +10,000	Iron, Steel

So, the answer will be option 1.