Follow

Did you know that a needle simply floated on water surface *is* a compass? It's so fun to share this kind of trivia with your kid! Mine thinks it's magic!

P.S. No they are not perfectly aligned with the phone. I trust the needle more.

flickr.com/photos/isagalaev/49

@isagalaev Really? You don't have to stroke it with a magnet to magnetize it first? Makes me want to duplicate this. And understand why.
Maybe during the manufacturing process where they pull the metal, it picks up the Earth's field, and in physically stretching the needle, it (mostly) aligns the domains along the needle's axis?
Or maybe radial electrostatic discharge from the tip during sewing caused the tip to be magnetized?
So we test new vs. used needles. Or just say it's magic.

@ericphelps all iron things align themselves along the lines of a magnetic field, they don't have to be magnets themselves physics.stackexchange.com/q/34 (afair). So as long as the needle can freely rotate, it would align with the only field that's everywhere, the Earth's.

@isagalaev Oh duh. Of course. So you can't tell where north is. Only the north/south line. Still, pretty handy! Thanks.

Sign in to participate in the conversation
Mastodon

Server run by the main developers of the project 🐘 It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!