Magnetisation And Magentic Intensity - Practice Questions & MCQ

 The magnetic intensity (H)-

The magnetic intensity of the magnetizing field is given by $H=\frac{B_0}{\mu_0}$
And its S.I. unit is $\mathrm{A} / \mathrm{m}$ while its C.G.S. Unit is oersted.
Magnetization (M) -
Magnetization is a process in which a normal material is converted into a magnetic material by exposing it to an external magnetic field. The magnetic intensity is the reason due to which a normal material changes into magnetic material.

We define magnetization M of a sample to be equal to its net magnetic moment per unit volume i.e $M=\frac{m_{n e t}}{V}$

Consider a long solenoid of n turns per unit length and carrying a current i 

The magnetic field in the interior of the solenoid is given by $\mathbf{B}_0=\mu_0 \mathbf{n I}$
If $n=\frac{N}{L}$ then $\mathbf{B}_0=\frac{\mu_0 \mathrm{NI}}{L}$ where $\mathrm{N}=$ number of turns and $\mathrm{L}=$ length of solenoid
Using $H=\frac{B_0}{\mu_0}$ So we can write $H=\frac{B_0}{\mu_0}=\frac{N I}{L}$
If the interior of the solenoid is filled with a material with non-zero magnetization then the material will magnetize.
And the field inside the solenoid will be greater than $B_0$.
The net B field in the interior of the solenoid may be expressed as

$
B=B_0+B_m
$

B - total magnetic field
$B_0$ - the magnetic field in a vacuum
$B_m$ - magnetic field due to magnetization of the material
And $B_m$ is proportional to the magnetization M of the material and is expressed as $B_m=\mu_0 M$

$
H={\frac{B_0}{\mu_0}}_{\text {we can write } B_o=\mu_0 H}
$

So we get $B=B_0+B_m=\mu_0 H+\mu_0 M=\mu_0(H+M)$
So we get

$
H=\frac{B}{\mu_0}-M
$

The Magnetization (M) of material is influenced by The magnetic intensity ( H )
So the relation between M and H is given as $\mathrm{M}=\chi \mathrm{H}$

where  is called magnetic susceptibility. And it is a measure of how a magnetic material responds to an external field.

Using $\mathrm{M}=\chi \mathrm{H}$ in $B=\mu_0(H+M)$
we get $\mathbf{B}=\mu_0(\mathbf{1}+\chi) \mathbf{H}=\mu_0 \mu_{\mathbf{r}} \mathbf{H}=\mu \mathbf{H}$
where $\mu_r=(1+\chi)$ is called relative magnetic permeability of the substance.
and $\quad \mu=\mu_0 \mu_r=\mu_0(1+\chi)$ is the magnetic permeability of the substance