School of Physics Lecture Demonstration Manual

Eh-5 The Barkhausen effect

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


To demonstrate the sudden alignment and realignment of the magnetic domains in a magnetic core.



Click on pictures to enlarge.

Barkhausen Effect Pic


A coil with thousands of turns of wire surrounding a core of magnetic material is connected to a P.A Amplifier.The signal from the coil passes through a high pass filter prior to going to the amplifier. When a magnet is moved close to the core the rearrangement of the magnetic domains causes the distinctive Barkhausen sound to be heard. If the core is replaced with an aluminium bar no Barkhausen sound is heard.

Safety notes

Electrical safety 


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