School of Physics Lecture Demonstration Manual

Eh-2 Hysteresis

Published: Tuesday 14 March 2006 - Updated: Tuesday 29 March 2011


To demonstrate the B-H hysteresis curve.



Click on pictures to enlarge.

Hysteresis Diagram 2

Hysteresis Diagram 1


As the variac voltage is increased the full B-H hysteresis curve to saturation is displayed on the C.R.O.

The voltage across the resistor R1 is proportional to the current in the primary and corresponds to the magnetic field strength H. The induced emf in the secondary is V=kdB/dt by Faraday's Law. The RC circuit (an integrator) yields a voltage proportional to B.

Safety notes

Electrical safety 


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