In this short piece of article, we will discuss magnetizing field intensity and intensity of magnetization. This is the topic of chapter magnetism and matter class 12. So let’s get started…
Magnetising field intensity
Definition: It is the ability of the magnetising field to magnetize a magnetic material when it is placed in any external magnetising field . It is expressed by a vector called magnetising field intensity or magnetic intensity.
Its magnitude may defined as the ampere-turns flowing through the unit length of the solenoid required to produce the following magnetising field. Thus
The dimensions of magnetising field intensity is . Its SI unit is ampere per meter . It is equivalent to or .
Intensity of magnetisation
As we know that when a magnetic material is placed in an external magnetizing field, it becomes magnetized.
Definition: The magnetic moment developed per unit volume of a material when it is placed in external magnetising field called intensity of magnetisation or simply magnetisation.
Thus, mathematically, the intensity of magnetization is given as
If is the surface magnetization current which has been set up in a solenoid of cross-sectional area and has turns per unit length, then the magnetic moment is developed at per unit length of the solenoid is . Therefore, the magnetic moment developed per unit volume of a solenoid of magnetization is given as
Now, consider a bar of magnetic material having cross-sectional area and length . Its volume is given by
Let’s suppose that the bar developed a pole strength at its end, when placed in external magnetising field, then the magnetic moment so developed is given as:
|Hence, the intensity of magnetization can also be defined as the pole strength developed per unit cross-sectional of the area of a magnetic material.|
The total magnetic field or magnetic induction inside a magnetic material is the sum of magnetizing field and the field arise due to the magnetisation of the material. Therefore,
SI unit of both and is the same .
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