Today’s Wonder of the Day was inspired by Elisa. Elisa Wonders, “how are magnets used” Thanks for WONDERing with us, Elisa!

Let’s start today’s Wonder of the Day with a joke. Ready? Here it is: What did the paperclip say to the magnet?

Any ideas? They said, “I’m really DRAWN to you!”

If you’ve ever used a magnet before, you may have seen that punchline coming. That’s because magnets attract many objects made from metal—including paperclips, nails, keys, and many other items. You’ve probably been around more than a few magnets in your day. But have you ever WONDERed how they work?

Magnets are usually made of iron or a material that has lots of iron in it, such as steel. They are great at attracting most metal objects. But you can hold a glass marble or plastic spoon against a magnet for as long as you like. Nothing will happen!

Much like the Earth, magnets have a pole at each end: a north pole and a south pole. You may not immediately notice the difference between a magnet’s poles. However, they behave quite differently. If you put the pole of two magnets near each other, one of two things will happen. If the poles are opposites, they will attract and click together. If the poles are the same, they will push away from one another.

It doesn’t matter whether you have a rectangular-shaped bar magnet or a curved horseshoe magnet. Both behave similarly. If you have time for an experiment, place an iron nail on a table with a magnet. Then, slowly push the magnet toward the nail. At some point, the nail will jump and stick to the magnet. This is because of the magnetic field.

Magnetic fields are invisible zones that surround magnets. Once a magnetic object enters the field, it is either attracted to or repelled away from the magnet.

Have you ever stuck a piece of art on a refrigerator door? If so, you already have some experience with magnetic fields. The attraction between the refrigerator door and the magnet holds the paper in place. As you may be able to guess, this means magnetic fields can actually pass through solid objects like paper.

Magnets can do so much more than just hang around on refrigerators, though. Did you know they keep the refrigerator door closed, too? You may be surprised to discover how many uses there are for magnets.

For example, magnets help with the recycling process. Recycling centers use magnets to help sort steel objects, such as tin cans, from other items. The magnet won’t help pick out the soda cans, however—aluminum isn’t magnetic.

Magnets can also be found inside computers, doorbells, and soda machines. They help electric can openers hold cans in place and cause compasses to point north. If you look closely, you’ll discover magnets tucked inside small pockets at the bottom of most shower curtains. The magnetic attraction keeps the shower curtain inside the tub, so you don’t end up with a flooded floor.

Where might you find some of the strongest magnets around? Not in a recycling center or on a refrigerator. Instead, you’ll find them in hospitals.

An MRI (magnetic resonance imaging) machine uses powerful magnets and radio waves. They give doctors a glimpse inside the human body. The strength of an MRI’s magnetic field is 20,000 times stronger than that of the Earth. As you can imagine, that’s one serious magnet!

Standards: CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, CCRA.W.4

#### Wonder What's Next?

Put on your hiking boots and join us in Wonderopolis tomorrow, as we trek across China to check out the greatest wall of them all.