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Remagnetising school magnets

From old to new - Cheap revival of magnets
Author: Holger Bach, Celle, Germany

Scholastic physics collections

Especially physics teachers will appreciate this application "Revival of old school magnets": Many physics collections in schools contain magnets that have lost their adhesive force over time. Buying new ones would be expensive, but you can use small and affordable super magnets to revive the old ones. How that works is explained below:

An old disused magnet

The flux density of these senile school magnets is only 14 mT (millitesla). Half a year before it was still 22 mT.

A relatively new magnet

This 6-month old magnet still has a magnetic flux density of 51 mT. Initially it was 100 mT.

Revival of old magnets

In order to revive older magnets we did the following: We placed 2 block magnets Q-10-05-03-N on each of the two pole surfaces and glued them on with an adhesive. (The super magnets also work on cylindrical and horseshoe magnets.)

The paperclip test

The result is illustrated by the paperclip test: The revived magnet on the right attracts visibly more paperclips than the older magnet on the left. The amount of paperclips near the pole is more significant than the length of the paperclip chain.

An amazing measurement

A quick measurement confirms: Instead of the original 14 mT the magnet now has more than 306 mT. Mission accomplished!


Safety tip:
Due to the dangers of chipping, advise your pupils to not let the magnets collide.

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