Let's Master the Wonders of Magnets!
Hello everyone! We use "magnets" all the time—to stick notes on the fridge or to make sure our pencil cases snap shut. They are very familiar objects, but they actually hide a lot of mysterious powers.
In this chapter, we'll have fun learning about what magnets stick to and the rules they follow! It might feel a little tricky at first, but if you recall the results of our experiments, you'll be just fine. Are you ready?
1. What Magnets Attract and What They Don't
When you bring a magnet close to various objects, some will snap onto it, while others won't react at all. Let's figure out the difference!
【Point】Magnets Love "Iron"!
The magical material that magnets can attract is "iron".
Let's check it using things around us.
- Things magnets attract: Nails, paper clips, steel cans, scissor blades, etc.
- Things magnets do not attract: 1-yen coins (aluminum), 10-yen coins (copper), plastic, paper, wood, glass, etc.
Common Mistake (Watch out!)
It’s easy to think "everything metallic sticks to magnets," but that's a mistake!
Example: Aluminum foil and 10-yen coins are metals, but they don't stick to magnets. Remember that, basically, only things made of iron will stick to a magnet.
【Summary】Magnet Property #1
Magnets attract iron. (They do not attract other metals, wood, plastic, etc.)
2. The "Poles" of a Magnet and Magnetic Strength
A magnet doesn't attract iron with the same strength everywhere. In fact, there are specific places where the force is strongest.
What are the "Poles"?
The areas at both ends of a magnet where the force is especially strong are called "poles". A bar magnet has two poles.
- N-pole: Usually colored red.
- S-pole: Usually colored blue or black.
Where is it strongest?
If you bring a bunch of paper clips toward a bar magnet, you'll see they stick mostly to the ends. Not many will stick to the middle. This shows that the "poles (the ends) have the strongest force."
【Fun Fact】What happens if you cut a magnet in half?
What do you think happens if you snap a bar magnet in two? Does it become an "N-only magnet" and an "S-only magnet"?
The answer is… new poles form at the cut, and you get two smaller magnets, each with both an N and an S pole! No matter how small you cut a magnet, it always keeps the mysterious property of having a pair of N and S poles.
【Summary】Magnet Property #2
The force attracting iron is strongest at both ends (the poles) of a magnet.
3. Attractive and Repulsive Forces Between Poles
Have you noticed that the feeling changes when you bring two magnets together? There is a set rule for this.
When they attract (stick together)
When you bring different types of poles together, they strongly attract and stick.
・"N-pole" and "S-pole" → Attract each other
When they repel (push away)
When you bring the same type of poles together, they are pushed back by an invisible force. This is called "repulsion."
・"N-pole" and "N-pole" → Repel each other
・"S-pole" and "S-pole" → Repel each other
【Memory Trick】
Just remember: "Magnets like someone different from themselves!" Imagine they get into an argument and push away if they are the same type.
【Summary】Magnet Property #3
Like poles repel, and opposite poles attract.
4. Distance and the Power of Magnets
Magnetic force works even without direct contact. Let's look at how it works through space and other materials!
What if there’s something in between?
Even if there is paper, a plastic sheet, or water between the magnet and the iron, the magnetic force can pass through them to attract the iron.
Example: Move a magnet underneath a desk to make a paper clip on top of the desk "walk."
How does distance change the attractive force?
When you hold a magnet near an iron paper clip, you will notice that the attractive force changes with distance:
- When close: The attractive force is very strong, and it easily pulls the iron or holds many paper clips.
- When far away: The attractive force becomes weaker. If the magnet is too far away, it cannot pull the iron at all.
Experiment idea: If you insert sheets of thick paper one by one between a magnet and a paper clip, the distance increases and the magnet's pull weakens, until the clip finally drops.
【Summary】Magnet Property #4
Magnetic force works through objects and across distance. The closer the magnet is to the iron object, the stronger the attractive force; the farther away, the weaker it becomes.
5. How Iron Becomes a Magnet (Magnetization)
Did you know that some iron objects can actually turn into magnets themselves? When iron is attached to or brought near a magnet, it gains magnetic properties. This is called "magnetization."
Iron becomes magnetized near or touching a magnet
When an iron nail or paper clip is stuck to a magnet, that nail itself becomes a magnet! You can easily test this by bringing another paper clip close to the tip of the nail: the second paper clip will stick to the nail just like magic. Some iron objects can even become magnetized simply by bringing them close to a magnet.
Making an iron nail stay magnetic
You can also magnetize an iron nail so it stays magnetic on its own:
1. Get one iron nail.
2. Touch one pole of a magnet (e.g., the N-pole) to the nail and stroke it repeatedly in the same direction.
3. The nail will then be able to pick up small paper clips by itself!
Common Mistake (Watch out!)
If you stroke back and forth (reciprocating), it’s hard for it to become a magnet. The key is to always stroke in "one direction only"!
Conclusion: Reviewing the Key Points
Let's review what we learned with these key points!
① Magnets strongly attract "iron"!
② Poles (N and S) repel if they are the same, and attract if they are different!
③ Magnetic force works across distance and through objects—the closer they are, the stronger the pull!
④ Iron objects become magnetized when placed near or touching a magnet!
Once you understand the properties of magnets, you can solve more interesting mysteries, like why a compass always points North. For now, go explore the things around you with a magnet and aim to become an "Iron Master"!