Make ferrofluid and chase it with magnets
A black liquid that makes spikes when a magnet gets near. Mind-bending.
How to do it
Pour 50ml of vegetable oil into a small flat-bottom dish. In a separate cup, mix 2 tablespoons of toner powder (or pre-made iron oxide powder — see supplies) with another 50ml of oil. Stir until smooth. Combine in the dish. Now bring a strong neodymium magnet under the dish from below — the black liquid forms perfect needle-like spikes that follow the magnet around. They will not believe it. Talk about why: tiny iron particles suspended in oil, each aligning to the field lines. Hand them the magnet — they chase the spikes for half an hour. Wash hands well after.
What you'll need
Iron oxide powder (Fe3O4)
AmazonStrong neodymium magnets
AmazonVegetable oil
FreeSmall dish
Free
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