physics question #59



Joey Bergen, a 12 year old male from the Internet asks on August 31, 1999,

Q:

Do permanent magnets lose their strength when they are dropped and if so, why? I took two magnets that were the same strength and dropped one several times. It then couldn't pick up as many paper clips as the other magnet.

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the answer

James Livingston answered on August 31, 1999, A:

Some old-fashioned permanent magnets made from steel can lose a bit of their strength when dropped or hit. Forces exerted on the magnet when dropped or hit cause very tiny motions of the atoms inside the magnet and these motions cause some of the atomic magnets to change their direction of magnetization. But ever since the 1930s, there have been magnets that are much better than steel. These include alnico magnets, ferrite (ceramic) magnets, and neodymium (rare earth) magnets. None of these modern magnets lose their strength from dropping (although if you drop them on a hard surface, they might break!). Steel magnets are no longer used in industry, but sometimes are still used for toys.

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