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This is the second post in my series of posts about forces. This week covers magnets, but over the next few posts I’ll talk more about electromagnetism and it’s explanation.
Magnetism
I started this class talking about magnets having a north and south pole and how they attract and repel each other. This is different than gravity which we talked about last week because gravity only pulls matter together, it doesn’t repel it. I also talked about how when magnets are broken in half each piece has a north and south pole. It is like there are a bunch of little magnets all stuck together to make a larger one. You can use the magnets from Popular Playthings Magnetic Match Rings to demonstrate this also because the donut magnets can be separated. I like these because it is easy to feel and demonstrate repulsion with these.
What is Magnetic?
You can have the kids check out what is attracted to magnets and what isn’t by bringing in a bunch of objects. I have some non-metal items here, but mostly I have different metals. The little coins are plated with silver, gold, and copper. You can separate Canadian money from US or Australian money with a magnet. Canadian 1, 2, 5, 10, and 25 cent coins are magnetic because they have steel cores, but coins from most other countries are not magnetic.
Repulsion From a Moving Magnet
Some metals like iron, nickel, and steel are strongly attracted to magnets. Other metals like copper and aluminum are repulsed when exposed to a moving magnet, as seen in these videos. You can see that moving magnets can generate an electric field.
The copper coin above displays repulsion behavior with the donut magnet. The coin I used is so light that it will stay on the donut magnet. You can put the copper one on a piece of styrofoam like the set up below and push it around with a strong magnet.
Earth’s Magnetic Field
Next, I showed the class a cartoon of the Earth’s magnetic field and told them that the field repels the charged solar wind that Earth is exposed to. Without it, the solar wind would remove the ozone layer around the earth. Then you can go through how people learned that there is a magnetic field on Earth. What is responsible for the Earth’s magnetic field? Earth’s core contains iron and nickle, and it churns around in the Earth and that is responsible for Earth;s magnetic field. You can show the kids a cartoon of the earth and show that the outer core is liquid. The movement of the iron in Earth’s core may also explain why the Earth’s magnetic field has flipped several times.
Naturally Occurring Magnets
People found lodestone which is a naturally occurring magnetic stone, in a city called Magnesia. That is how magnets got their name. Eventually, people used this stone to make compasses. Then you can show the kids a compass and show them how to use it.
Make Your Own Compass
The last activity is to have kids make their own compass. You need a pie tin filled with water and a piece of cork or styrofoam. You will also need a needle and a magnet. Rub the magnet on the needle around 20 times with the magnet, then place it on the styrofoam and you can see that it points north just like the compass. Magnets can magnetize a metal. That is what you are doing when you rub the magnet on the needle. You can move a compass needle with a magnet. The kids really thought that was cool.
Magnets can create magnets and magnets can create electricity, but how was the lodestone people discovered magnetized? Not all lodestone is magnetic. One theory is that it was magnetized by lightening strikes.
Finally, I had the kids break up into groups and try the activities themselves. They drew pictures in their lab notebooks about what they were experimenting with.
For more STEAM activities, take a look at my Pinterest board.