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Series of experiments

Stunning and educational experiments for pupils
Author: Florent Coulon, Besancon, France, [email protected]
Online since: 10/03/2009, Number of visits: 409572
Mr. Coulon is a teacher at the grammar school E. Belin de Vesoul. He regularly conducts magnet experiments with his students. Some of them he captured on video. The first two videos demonstrate the strong adhesive force of our huge disc magnet 45x30 mm.
In video 3 and 4, Mr. Coulon experimented with two large copper discs and super magnets (disc magnet and block magnet Q-40-20-10-N); here the Faraday Induction Law can be illustrated.
Have fun watching and doing it yourself - but always wear thick gloves like Mr. Coulon!
The physical explanation for this remarkable deceleration is the Faraday Induction Law:
Dropping the magnet causes a B-field flow change in the conductor board (copper in this case). That induces circular currents in the conductor (Foucault currents, green in the graph).
The induced currents in turn produce a magnetic field, which is opposite of the falling magnet (Lenz's Law), which slows it down.
The same effect can also be seen in the fourth video:
The Foucault currents induced in the copper discs cushion the moving speed of the magnet that is dropped in between.
Note from the supermagnete team:
Further experiments on the topic of induction can be found here.