It has now been over 100 years since Heinrich Barkhausen published his description of a crackling sound heard when a piece of iron is magnetized inside of a coil wired to a set of headphones, and this phenomenon provided evidence for the theory of magnetic domains. Traditionally, this effect is performed as a demonstration by connecting the coil to an audio amplifier, such as one used for electric guitars.
References
1.
H.
Barkhausen
, “Zwei mit Hilfe der neuen Verstärker entdeckte Erscheinungen
,” (Two Phenomena Discovered with the Help of New Amplifiers), Zeitschrift für Physik
20
, 401
–403
(1919
).2.
In
R.
Feynman
, The Feynman Lectures on Physics
, Vol. II, Chap. 37-3. Feynman describes magnetic domains and all their nuances.3.
For a good video of the traditional Barkhausen effect demo, try MIT’s at https://www.youtube.com/watch?v=YLycGnOCqLc. Note the electromagnetic noise picked up by the amplifier.
4.
Jan-Peter
Meyn
, “Demonstrating the Barkhausen effect with high signal-to-noise ratio
,” Eur. J. Phys.
38
(4
), 045502
(May
2017
).© 2020 American Association of Physics Teachers.
2020
American Association of Physics Teachers
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