A watch problem

[einsteinsdog]

My watch has become magnetised by leaving it on an appliance. How can I demagnetise it without going to a jeweller?

[Buenchico]

It's a long while since I taught physics but i seem to remember that the basic theory: Leaving something in a steady magnetic field willmagnetise it and placing it in a rapidly alternating field will demagnetise it. The easiest place to find a rapidly changing magnetic field is next to an electrical transformer. You could try leaving the watch on top of (or next to) a small transformer such as the one in your mobile phone charger or in the power lead for your CD player. If this isn't powerful enough, there are plenty of bigger transformers (with bigger alternating magnetic fields) inside your mains operated electrical equipment but I can't actually recommend that you start poking around inside unfamilar equipment! (I've worked on live equipment for nearly 40 years - and connected myself to the mains on many occasions in the process - but I've always taken plenty of precautions. Just remember that jewellers are cheaper than undertakers!).

Chris

(PS: This information is provided in good faith but, if your watch starts going backwards, please don't blame me!).

[THECORBYLOON]

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