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explain how magnets work

Topspy

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Topspy
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Sep 22, 2006
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hey all:

just curious: I'm not a physics major or an engineer, just an electronics buff and mechanical nut. I do have a good grasp on the basics though. Still, would someone explain to me how magnets seem to defy gravity? I have several sticking to the fridge, obstaintly disobeying gravity even tho subjected to a steady 1G pull. Some more than others lol. A layman's explanation would be helpful. thanks!
 
If you lay the fridge door down flat with the magnets on top, they no longer defy gravity. But have the magnets changed internally to do that? What do you think?
 
If I lay a book down on top of the fridge when it's flat, I get the same result. The oddity is when you stand the fridge up, the book falls off, the magnets don't.
 
Or did the book change internally? IT'S ALL IN MY MIND
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
nice try tho. anyone? anyone?
cuddles? piggy? all y'all?
 
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Why should gravity get to be in charge?

If the magnet fell off the fridge, gravity would be defying magnetism!

But seriously, there's no answer, really. That's just the way the world works. Masses exude gravity. Magnets exude magnetism. (Metaphorically.)
 
Topspy said:
If I lay a book down on top of the fridge when it's flat, I get the same result. The oddity is when you stand the fridge up, the book falls off, the magnets don't.
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But what if you glue the magnets on. Then you wouldn't know if it's glue OR the magnetism, would you! So they must be the same! Magnetism = glue!
 
69dodge said:
Why should gravity get to be in charge?

If the magnet fell off the fridge, gravity would be defying magnetism!

But seriously, there's no answer, really. That's just the way the world works. Masses exude gravity. Magnets exude magnetism. (Metaphorically.)
Click to expand...

Yeah. You can buy magnetism in tubes at the hardware store. It's called "glue".
 
Friction holds the magnets up. The force of friction between two surfaces is more or less proportional to how hard the force is that holds them together. Because magnets attract themselves to the refrigerator pretty well, there is more friction between a magnet and a refrigerator door than there is between a non-magnetic object and a refrigerator door. The friction balances out the force of gravity.

Glue is something different, although similar on a fundamental level.
 
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baron's link is a good one. But, if you want a very condensed version, there are four known forces in the universe: strong, electromagnetic, weak, and gravity. I listed them in order of strength. Note that electomagnetic is stronger than gravity.

So, stick a magnet to a piece of metal, and turn it so the magnet is upside down, hanging in the air. Will it fall or stick? Well, given that the electromagnetic force is stronger than gravity, it will stick.

The weak and strong forces only work in very small distances (10^-18(m) and 10^-15, respectively), and so can be ignored in this analysis.
 
I'm confused now.
So what's the Schwarzchild radius of a fridge? Does this explain where all my white wine went?
(I keep it in the fridge, because the fridge magnets improve the vintage).
 
http://van.physics.uiuc.edu/qa/listing.php?id=434
Some kinds of metals (like steel that the needles are made of) are made up of billions and billions of individual atoms that each have the properties of a microscopic magnet. The atoms in steel naturally tend to get together in tiny little groups called domains, and within each domain the atoms tend to point in the same direction, which makes the domains behave like a tiny little bar magnets just like the kind you have probably played with at school...

if you bring the needle close to another magnet of some kind, (like the ones on your fridge, or better yet some stronger ones you can find in your classroom) something interesting can happen: Because of the other magnet you are holding it near, the little domain magnets in your needle will tend to line up so that they are pointing along the same direction.
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Make your own magnet

Magnets are cool. The way they work is simple. Any other questions?

More on magnetism
 
Topsy, I don't think Zep's first reply was meant to be flip, but was honestly meant to get you to think about your question. In classical physics, gravity is a force and so is magnetism. Depending on how you orient the things you're talking about, they can be made to "defy" one another or to work together, or at an angle, etc.

So your question isn't clear. Do you really want to know about the nature of magnetism compared to gravity, or just how in everyday life these things can interact?
 
By the way--in the refrigerator magnet situation, don't forget about friction!

By the way--as a juggler, I frequently hear the "defies gravity" thing. If it weren't for gravity, I couldn't possibly juggle--well, at least not in any way I'm familiar with now. I assure you, the refrigerator magnet is not "disobeying" gravity.
 
Yeah, if you pick up the magnet, and drop it, it will FALL.

It sticks to the fridge (metal) because of magnetism, not because it is defying gravity. A weak enough magnet (like those found in shoes or other products claiming to cure stuff with magnets) won't even stick to your fridge!
 
Eos of the Eons said:
Yeah, if you pick up the magnet, and drop it, it will FALL.

It sticks to the fridge (metal) because of magnetism, not because it is defying gravity. A weak enough magnet (like those found in shoes or other products claiming to cure stuff with magnets) won't even stick to your fridge!
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As others have pointed out, friction is also involved. If there was no friction between the magnet and the fridge, the magnet would slide down the door until it hit the bottom of the fridge door. At that point magnetism would attempt to stop the fall, but would probably lose due to the accumulated magnetism.

I am, of course, ignoring the insignificant amount of magnetic braking caused by the moving magnet inducing an electric current in the fridge that dissipates some of the fall.

But if you want a really cool "magnet vs gravity" effect, see http://hyperphysics.phy-astr.gsu.edu/hbase/solids/maglev.html.

Cheers,
Ben
 
UserGoogol said:
Friction holds the magnets up. The force of friction between two surfaces is more or less proportional to how hard the force is that holds them together. Because magnets attract themselves to the refrigerator pretty well, there is more friction between a magnet and a refrigerator door than there is between a non-magnetic object and a refrigerator door. The friction balances out the force of gravity.
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Umm, no.

If you hold the fridge door so it's horizontal with the magnet hanging underneath it still stays stuck to the door. Please explain how friction is responsible for that.
 
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