Warning: this question involves a lot of physics knowledge. Not for the faint hearted.?
Ok so over the past month I was studying magnets and I tried connecting them with coins (1p, 2p, 5p, 10p you get the idea) and it seemed quite weird how the 1p and 2p coins from 1970-1988 didn't connect to the magnet and how the both coins From 1900-2018 are magnetic. How?
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answers:
Steve4Physics say: Coins are made of various alloys which make the coins hard-wearing. The alloys generally contain copper and nickel. and sometimes small amounts of zinc and tin. Some coins are actually steel (iron) which are copper-plated or nickel-plated.

The alloy used to make even the same value of coin change from time to time. See link.

Ferromagnetic metals are attracted to magnets. These are iron (used to make steel), nickel and cobalt. Some of you coins contain steel or nickel - and those are the ones attracted to a magnet.
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ksgentleman70 say: Well, I'll have to go out into left field with this one.....

I'd say because of the amount of ferrous metal put into the coins during those years.
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Vaman say: It is simple copper is a good conductor. It can not retain magnetic field and it can not be magnetised. So it will not stick. Reduce the softness in copper, other metals are added. May be these coins have iron mixed with them. These iron particles can be magnetised and they stick. Those sttick are not pure copper coins.
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xxlpb say: wjyxeofh
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