Question

Susceptibility of ferromagnetic substance is
A. >1
B. <1
C. 0
D. 1

Answer 1

Magnetic susceptibility is defined as the extent to which a material can be magnetised in a given magnetic field. Its mathematical representation is given below. There are three types of material classification based on magnetic susceptibility. They are diamagnetic, paramagnetic, and ferromagnetic in increasing order of magnetic susceptibility.

Formula used:
$\chi =\dfrac{M}{H}$

Complete step-by-step answer:
Magnetic susceptibility is defined as the extent to which a material can be magnetised in a given magnetic field. It is represented by the symbol $\chi$. It is mathematically represented as
$\chi =\dfrac{M}{H}$
Here M is the magnetisation of the substance and H is the field strength.
Using magnetic susceptibility objects can be broadly classified into three different types

1. Paramagnetic Material: These are materials that align themselves in the magnetic field and have positive magnetic susceptibility. Although positive this number is not very high. Alkaline earth metals, aluminium etc are paramagnetic.
2. Diamagnetic material: These are materials that align themselves against the magnetic field. Their magnetic susceptibility is negative. Gold, mercury etc are diamagnetic in nature.
3. Ferromagnetic Material: These materials are highly magnetised in a given magnetic field. Their magnetic susceptibility is positive and very high. magnetic susceptibility of ferromagnetic materials is in the range of 1000-10000. Iron, cobalt etc are ferromagnetic in nature.

So, to answer the question, Susceptibility of ferromagnetic substances is >1.
Therefore, Option A is correct.

So, the correct answer is “Option A”.

Note: The high magnetic susceptibility of ferromagnetic substances makes it very useful for a variety of purposes. They are used to make non-volatile information storage devices that store digital data like hard drives, tapes etc. They are also used to make permanent magnets that are further used in turbines, motors etc.