This week we spent one whole morning (plus a bit of the afternoon) exploring magnets.
We started out by reading a chapter of The Magic School Bus: Amazing Magnetism.
I was delighted to find that the story is structured around a competition, the prize for which is a pizza party – this was a book that was going to appeal to at least two of J(7)’s passions! We read chapters in between doing our own experiments, which kept J nicely engaged.
Making a Magnet
We stroked a magnet along a needle in the same direction about twelve times to create a temporary magnet.
A magnet is made up of many tiny mini-magnets, or “domains”, which all line up and point the same way. Any metal that sticks to a magnet also has domains. These are jumbled up – but a magnet can make them line up, and the metal temporarily becomes a magnet.
When we dropped our needle magnet on the table a few times, the domains became jumbled again and the needle was no longer magnetic. Heat also jumbles the domains.
One of the books we used, Magnet Science, comes with a sealed transparent box of iron filings. We observed the patterns the iron filings made when we applied different shaped magnets. The patterns showed us each magnet’s invisible magnetic field lines.
I gave each child a glass of water with a paperclip at the bottom and challenged them to remove the paperclip without putting their hand in the water. Straight away they dipped the magnet into the water, so I had to add “… and without getting the magnet wet”, at which point they figured it out!
We used the fact that magnets with the same poles repel each other to create a cool illusion. We forced two repelling magnets together with a couple of pencils in between, and taped the magnets together. On removing the pencils, magnetic force keeps the top magnet hovering in mid-air!
Measuring Magnetic Force
We placed a paperclip at the zero end of a ruler and a magnet at the other end. Then we slowly moved the magnet towards the clip and recorded the distance in centimetres between the two at the point when the clip jumped onto the magnet. We tried this with different magnets to compare their strengths.
Magnetic Force and Gravity
This time we taped the zero end of the ruler perpendicular to the table and repeated the measuring process. We noted that this time the magnet had to be closer to make the clip jump, because its force is competing with another force – gravity.
Making a Compass
We taped a bar magnet to the base of a small plastic pot and floated the pot in a large bowl of water. After leaving the water and magnet to settle for a minute, we used a dry wipe marker to mark (on the large bowl) where the north and south poles of the magnet pointed. When we turned the magnet pot around, it returned to the same spot, its poles aligned with the Earth’s magnetic north and south.
(Happily, this confirmed our recent discovery, when we were learning about the beginning of Islam, that Mecca is in the direction of our pear tree!)
We taped magnets to the underside of a piece of cardboard, propped it up to make a ramp, and raced metal and glass marbles down it. We used our strongest magnets and an old iPad box, but it was difficult to see whether the magnetic marble or the glass marble won the race – I think we would have seen better results with a longer ramp.
We put a piece of paper on top of a magnet and made our own executive toy – paperclip sculpture. 🙂
We looked at pictures of magnetite, a naturally magnetic rock first found at a place called Magnesia in Ancient Greece.
The Magic School Bus: Amazing Magnetism gave us a story to structure our experiments around. The best experiments came from The Usborne Book of Science Activities Volume One. We also used Magnet Science (Hands-on Science), which comes with iron filings and a set of magnets.
This Squidoo lens has stacks of magnet ideas and links to resources.
Steve Spangler explains what magnets are and talks about their history. More experiments here too.
The children’s interest in magnetite and in the causes of the Earth’s magnetic forces (not to mention Minecraft) got me thinking that this could be a good time to find out more about rocks. Watch this space!
Magnetism also relates to electricity, which C explored in a recent project. (We loved The Magic School Bus and the Electric Field Trip, which taught me a few things about electromagnetism.) We’ll come back to this topic next time we look at magnetism.
Do you know of any fun magnet experiments?
For more science posts, visit Science Sunday at Adventures in Mommydom.