= Magnetic hysteresis
{wiki}
To understand the graph, first learn/remember the difference between the <magnetic B and H field>.
The interest of the \x[magnetic hysteresis]{magic} graph is that it serves as an important characterization of a :
* its area gives you the hysteresis loss of the <transformer>, which is a major cause of efficiency loss of the component
* some key points of the curve give important characterizations of the core/material:
* <Saturation magnetisation>
* magnetization strength without field
* how much field you need to demagnetize it
This curve will also tell you how many turns of the coil will be needed to reach the required field.
\Image[https://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/StonerWohlfarthMainLoop.svg/512px-StonerWohlfarthMainLoop.svg.png]
{height=600}
{title=Theoretical magnetic hysteresis plot}
\Video[https://www.youtube.com/watch?v=pXukVix5Pcw]
{title=Measurement of B-H characteristic}
{description=
1989. 1989 and they were making such awesome materials. It is hard to understand why university still exists given this.
Shows how you can obtain the \x[magnetic hysteresis]{magic} curve with an <AC source> plus an <oscilloscope in XY mode>. https://youtu.be/pXukVix5Pcw?t=193 clearly shows the measurement circuit.
}
\Video[https://www.youtube.com/watch?v=YiKFPyfC1HY]
{title=\x[Magnetic Hysteresis]{magic} experiment by <UNSW> Physics.}
{description=
2020, thanks <COVID-19>. Like other <UNSW Physics YouTube channel> videos, the experimental setup could be made clearer with diagrams.
But this video does have one merit: it shows that the hysteresis plot can be obtained directly with the <oscilloscope XY mode> by using an <AC source>. The Y axis is just a measure of the total magnetic field induced by the primary coil + the magnetization of the material itself.
}