Good Article. At school aged about 12-13 we were taught how to improvise a compass in Physics class, some folks could even get the needle to float on the dish of water without the paper just using surface tension after magnetising the needle with some insulated coiled wire and a PP3 battery. We were also taught how to make a little electric motor from some magnets, insulted wire, cotton bobbin, battery (making the split ring commutator was always tricky though) etc.
Bear Grylls in his video should have validated his little experiment with a proper compass for the viewers as floating a needle using a dry leaf on water can point in the wrong direction due to wind shear on the leaf, the magnitisation force is very weak as so is not entirely reliable.
Rubbing the needle in the hair is probably just to degrease the needle so as to improve the water surface tension rather than the belief that it is actually magnetising the needle.
Edited by Am_Fear_Liath_Mor (12/03/09 06:57 PM)
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