Magnetic forces | Forces at a distance | Middle school physics | Khan Academy

Let's talk about magnets and magnetic forces. Magnets are these neat objects that are able to attract metals like iron. Magnets are used in all sorts of things, from holding paper on your refrigerator to computers to compasses. So, magnets can be used to stick things together, point us in the right direction, and even lift things, and they do this through magnetic forces.

If you've handled two magnets, you've felt magnetic forces, even when the magnets weren't touching each other. That's because magnetic forces are non-contact forces, which just means they can affect other objects they aren't even touching. Magnets will attract or repel each other, and this attraction or repulsion is a magnetic force. But magnetic forces don't affect everything the same way; otherwise, a magnet would stick to you, not just a refrigerator.

In this video, we're going to talk about the magnetic forces between two magnets. So why do magnets sometimes attract each other and other times repel each other? Well, this has to do with the orientation of the magnets. Orientation is really just a fancy word for how the magnets are positioned compared to one another.

You see, it turns out that each magnet has a north and a south pole. But what does this have to do with attraction or repulsion? Well, as you may have heard, opposites attract. So if you face the north pole of one magnet to the south pole of another magnet, guess what? They will be attracted to each other. But if you turn one of those magnets around so that you have two north poles facing each other, they will repel. The same thing would happen if it was two south poles facing each other.

So the direction of the magnetic force completely depends on the orientation of the magnets. Orientation, though, is just one thing that affects magnetic forces. The strength of magnetic forces depends on a couple of things. For one, distance. If you've ever held two magnets, you may have noticed that when you move them closer, they seem to almost jump together. Or, if you try to push two like poles together, they get harder and harder to hold together the closer you get.

This is because magnetic forces depend on distance. The closer the two magnets are together, the stronger the force between them. So as the distance decreases, the force increases. But the farther away they are, the weaker the magnetic force is. So, distance increases, force decreases.

The other big factor that affects how strong a magnetic force is, well, the magnets themselves. Some magnets are really weak, like a lot of refrigerator magnets. Others are so strong that even tiny ones can be almost impossible to pull apart. Some of these stronger magnets are even used to make high-speed trains levitate off the ground.

And yes, this rectangle is supposed to be a train. While my drawing isn't amazing, the fact that magnetic forces can levitate a train is incredible.