Magnetic Field Intensity Unit
Magnetic field intensity is also known as the magnetizing force which is measured is ampere-turns per meter (A-t/m).
Of primary concern, however, is the magnetomotive force needed to establish a certain flux density, B in a unit length of the magnetic circuit.
Magnetic Field Intensity Formula
The letter symbol for magnetizing force (magnetic field intensity) is H. The following relationship defines H as;
ℑ =applied MMF in ampere-turns
l =average length of the magnetic path in meters
Find the magnetic field intensity in the magnetic circuit shown below:
We can calculate the intensity using following formula:
If the dimensions of the magnetic path were changed, the value of H would also change. Fox example, if the total length of the magnetic path doubled, we should expect the value of H to decrease to one-half its previous amount.
If physical dimensions are double for the above circuit, then magnetizing force will be;
So, we can observe that, for a given number of ampere-turns, the magnetizing force varies inversely per unit length of the magnetic path.