All magnets have a north and a south pole. But where are the north and south poles on flat refrigerator magnets?
The proofs are done on my new book and I can hardly wait until it comes out in November (Have you pre-ordered your copy yet?). It turns out that in trying to make 365 projects fit into about 250 pages my editors left out a project – this project – in the middle of the book. So I ended up writing another to put at the end, which means I can share the lost project with you here.
Consider this a preview. Each project in the book has the same sections as one below. Do it! and What happens? gets the kids started and What if? gives ideas for exploring further.
So grab a couple refrigerator magnets and get started!
2 flat rectangular refrigerator magnets
Stick the refrigerator magnets together one on top of the other. Do they stick together? Try putting them top to top together and bottom to bottom together. In what layouts do they stick together? In what layouts do they not stick together?
Arrange the magnets so they stick together. Slide the magnets across each other long ways. Then slide them across each other short ways. Rotate one magnet half a turn and slide again. What do you observe?
The magnets only stick together when you put their black bottom sides together. You can slide the magnets smoothly in most configurations. But when they are aligned the right way you will feel bumps or a vibration when you slide the magnets. This is because the magnets are made of parallel rows of north and south poles on just one side of the magnet. They are set up like rows of tiny horseshoe magnets. When those rows are lined up on both magnets and you slide across the rows, the north and south poles push and pull as you slide the magnets causing a bumpy vibration.
What if you use refrigerator magnets that are not rectangles, such as a circle or some other odd shape? How are the poles arranged in these magnets?