Touch a needle with a screwdriver and nothing unusual should happen (unless the screwdriver is already magnetized). Now, take some of the needles and hold them against the end of a magnet for a while (the stronger the better). After doing this, you will have turned each needle into a little magnet, and when you touch them with a screwdriver they will stick to it.
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. The needle of a compass is also a bar magnet, and we know what this does: it points north because it likes to line itself up with the magnetic field of the earth.
When you make a piece of steel (like a needle), all of the tiny domain-magnets inside tend to get stuck pointing in different directions, which means that they more or less cancel each-other out, so to begin with the needle does not behave much like a magnet at all.
However, 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. (You can visualize this by holding two bar magnets near each other and noticing how they like to line up a certain way). The domains in the needle will do the same thing, and after you take the needle away from the other magnet, the domains in the needle will tend to stay pointing this way (they sort of get stuck pointing in the same direction). Now, since you have lots of these little domain magnets in the needle all pointing in the same direction, the needle will itself have become a small magnet. (This is exactly how bar magnets are made).
Magnets attract other magnets (as you can see), and also attract some kinds of metal like many kinds of steel. If you touch your magnetic needle with a steel screwdriver it will stick. However, stainless steel is not a very good magnetic material, so if you touch your magnetic needle with something made of stainless steel it will probably not stick (try it).
How Do Magnets Work?
Large-scale magnetism, like the kind observed in bar magnets, results from magnetic fields that naturally radiate from the electrically charged particles that make up atoms, said Jearl Walker, a physics professor at Cleveland State University and coauthor of "Fundamentals of Physics" (Wiley, 2007). The most common magnetic fields come from negatively charged particles called electrons .
Normally, in any sample of matter, the magnetic fields of electrons point in different directions, canceling each other out. But when the fields all align in the same direction, like in magnetic metals, an object generates a net magnetic field, Walker told Life's Little Mysteries.
Every electron generates a magnetic field, but they only generate a net magnetic field when they all line up. Otherwise, the electrons in the human body would cause everyone to stick to the refrigerator whenever they walked by, Walker said.
Currently, physics has two explanations for why magnetic fields align in the same direction: a large-scale theory from classical physics, and a small-scale theory called quantum mechanics.
According to the classical theory, magnetic fields are clouds of energy around magnetic particles that pull in or push away other magnetic objects. But in the quantum mechanics view, electrons emit undetectable, virtual particles that tell other objects to move away or come closer, Walker said.
Although these two theories help scientists understand how magnets behave in almost every circumstance, two important aspects of magnetism remain unexplained: why magnets always have a north and south pole , and why particles emit magnetic fields in the first place.
"We just observe that when you make a charged particle move, it creates a magnetic field and two poles. We don't really know why. It's just a feature of the universe, and the mathematical explanations are just attempts of getting through the 'homework assignment' of nature and getting the answers," Walker said.
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