Magnetic repulsion demo. You can’t push them together. This is a popular demonstration of magnetic repulsion. You try to bring the North poles of these magnets together but physically can’t. You start feeling the invisible field at about 10 cm and it becomes stronger than you are at about 2 cm. It is a spooky feeling.
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Although the force required to make them touch is only about 15 kg, the force also pushes away from center so it becomes increasingly hard to stabilize as it gets closer. Even strong people can’t cope with a 15 kg repulsion plus a 15 kg sideways force using outstretched hands.
This uses NIB (Neodymium-Iron-Boron) super magnets about 2.5 cm by 1.5 cm very roughly taped. They are in a PVC tube to prevent opposite poles crashing together, so are safe for kids to use. The string is just so I can tie it to a desk if need be.
This is a great demo for adults and kids alike and most people are happy to try. When the kids can’t do it you give it to the macho blokes who also can’t do it. After I have done my free shocks demo they can get a bit apprehensive though.
I have thought of having a seat with a number of these magnets in a tube supporting each leg. You could put several in each leg to add the 15 kg force. Three magnets in each leg would give 30 kg each or 120 kg total.
Siobhan gets asked to push the magnets together.
Related pages
Try something else
External links
Levitation by induction – YouTube
Photo Date: August 19, 2012