To understand the graph, first learn/remember the difference between the magnetic B and H field.
The interest of the magnetic hystereses 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:
This curve will also tell you how many turns of the coil will be needed to reach the required field.
Figure 1.
Theoretical magnetic hysteresis plot
. Source.
Video 1.
Measurement of B-H characteristic
. Source.
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 magnetic hystereses curve with an AC source plus an oscilloscope in XY mode. clearly shows the measurement circuit.
Video 2.
Magnetic hystereses experiment by UNSW Physics.
. Source.
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.

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