# Magnetic field intensity and density

1. Oct 25, 2015

### nitishsharmabit

Hello folks,

Can anyone explain to me what is the difference between magnetic field intensity H and magnetic field density B?

2. Oct 25, 2015

### Henryk

Hi
In the simplest terms, the magnetic field intensity H relates to the sources of the magnetic field. For example, the integrated H in a magnetic loop is related to the total current enclosed by the loop (time-independent) by the relation
$$\oint \vec H \cdot d \vec l = I$$
This equation is true regardless of the magnetic permeability of the loop.
whereas intensity B describes effects of the magnetic field. Examples are Lorentz force on a charge moving in the magnetic field $\vec F = q (\vec B \times \vec v)$
and induced EMF in, say, a single winding of a transformer $EMF = - \frac d {dt} \iint \vec B \cdot d \vec S$

3. Oct 26, 2015

### nitishsharmabit

That means B is property of material since it depends on the magnetic permeability of the loop.

4. Oct 27, 2015

### Henryk

Well, strictly speaking, the property of the material is the magnetization vector, usually denoted as M. B is the total effect of the source field H and material response in terms of polarization M, such as $B = \mu _0(H +M)$

5. Oct 29, 2015

### nitishsharmabit

Thanks!! Can you provide me a link where it has been discussed in detail?

6. Oct 29, 2015

### Henryk

I'm a physicist, I just know it.

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