Topics Covered: magnet, magnetism, field force, magnetic dipole, induction, magnetic field
Have you ever played with a magnet? If so, have you ever wondered why a magnet only attracts certain objects? Why do two magnets sometimes attract but sometimes repel? Today, we will address these questions and talk about the fascinating properties of a magnet that makes it so magical.
Let’s start off with the basics. Every magnet has two ends, each known as the north pole and south pole. Here, the phrase “likes repel and opposites attract” holds true again. When you put the north poles of two magnets closer together, they will repel. But when you put the north and south pole of two magnets together, they will attract! This also tells us that a magnetic force is a field force— just like electric force, magnetic forces act on an object without physical contact!
Now, imagine you cut a magnet in half. What do you think would happen to the magnetic poles? Surprisingly, cutting a bar magnet in half will produce two weaker but still complete magnets, each with a north pole and a south pole. And this will continue even if you cut the magnet smaller and smaller! In fact, the basic unit of magnetism (magnetic force) is a magnetic dipole. There will never be a monopole!
Can we play around with a magnet a little bit more? If you put a bar magnet near a paper clip, a paper clip will stick to a magnet— this is probably not surprising. But what’s fascinating is that once a paper clip is stuck to a magnet, it will act like a weak magnet itself, attracting other paper clips even if that paper clip is not directly attached to the magnet! In other words, it is magnetized and the magnetism is induced. One thing to note: the paper clip is only temporarily magnetized and will lose its magnetic force after a certain amount of time.
Let’s sum up what we observed about magnets. Magnets are metal (usually iron, cobalt, or nickel) and exert a long range force. Opposite poles attract while like poles repel, and magnets can induce magnetism in objects that are attracted to magnets. Lastly, magnets are surrounded by a field of force; this force is known as the Magnetic Field (with symbol B), and this cool magnetic field will be a topic for the next time! In the meantime, have some fun with magnets :)
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