I’ve read somewhere that magnets dont do work so they dont use energy, but then how come they can move metallic objects? where is that coming from?
In: Physics
It’s kind of weird. I don’t think there’s a way to fully explain it because Physics only knows so far.
Magnets work because they have a “charge”. Atoms like to have a certain number of electrons. Magnets are made of a material that either has too many or not enough of those electrons. When something is “charged” like that, it will attract other atoms to try and form combinations of atoms that have the “right” number of electrons. Actually a TON of chemistry is about just learning the “rules” atoms tend to follow so you can predict what happens when you mix different ones together.
So the reasons magnets “pull” or “push” things has to do with atoms REALLY wanting to have the “right” number of electrons.
This is the part that’s weird: this doesn’t “use” energy. It’s just how the universe works. We might have to spend energy to “charge” the magnet by changing how many electrons its atoms have. The pushing and pulling may do work by changing the kinetic or potential energy that other things have. But we don’t really have to do things to the magnet to make it do that. There’s no “battery” or other way to “power” it. It just is, and this concept of atoms with charges pushing or pulling each other is just a thing Physics says happens with no explanation.
COULD there be some reasoning? Sure, we’re always trying to understand it. If we could figure out WHY this “just is”, maybe we could figure out ways to make it happen with other materials. In theory that could help us have free energy or maybe some other crazy things. But so far we haven’t had much success figuring out the WHY.
And it’s not much use for free energy on its own. Yes, I can use a magnet in my hand to push things. But those things push against the magnet, which pushes against my hand, which causes forces through my body to push against the ground through my feet. In other words, the magnet doesn’t do any work, my body does work. We know ways to use magnets to do interesting things, but we usually have to use energy for something to MOVE the magnet to make that happen.
(Also: yes, I can lift heavy objects with magnets on the ground. But remember, atoms REALLY like having the “right” number of electrons. To make a VERY strong magnet, I need atoms with a VERY wrong number of electrons. The universe hates this so much you can’t just make a piece of metal be this “wrong”. The only way to make SUPER strong magnets is… electromagnets. Those do work to constantly MOVE electrons through a material to generate a field. It’s kind of like I’m constantly spending energy to make the atom “wrong”, then the universe is “fixing” it, then I spend more energy making it “wrong” again. These super strong magnets can’t stay super strong because the universe very quickly balances things back out by redistributing electrons UNLESS I’m spending energy to unbalance it again. (In fact, it’s not really changing between “right” and “wrong”, it’s more like I’m “pushing” or “pulling” electrons into the atoms, and the universe is “pulling” or “pushing” back, and I have to work harder than the universe to keep the magnetic field active.))
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