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Once the candle lit, the small ring of nickel previously attracted by the magnet will stop being attracted to it and will hang in the vertical piece of wood.
This phenomenon is caused by the fact that the material at a certain temperature, called the Curie Point temperature, lose their magnetization.
However, if the wire attachment allows the free movement of a pendulum, if the ring is not too heavy, it can start to oscillate and possibly recover after cooling its ferromagnetic properties and then come back on its original position. ..
And what about the rocks ?
more attached !!