How to Build an ON/OFF Switch for a Permanent Magnet

Watch and see how a magnetic switch can be built in a few simple steps by using 3 equal magnets and iron bars.
Interesting Engineering

Ever wanted to build a magnetic switch for a permanent magnet?

Of course you have. Instead of prying a strong magnet from a metal surface a switch takes away the magnetic force instantly. And imagine the tricks you can play on your family.

But how is this possible?

Watch and see how a magnetic switch can be built in a few simple steps. The switch is built with 3 equal magnets and you will need some iron bars.

It’s obviously not possible to turn off the magnetic field of a permanent magnet. But science empowers you to manipulate the situation. By playing around with various magnets and creating different interactions it is possible to alter the magnetic field.

Precision is key. You can’t use three random magnets you find in your home. They must be of the same size and strength for the magnetic fields to eventually collapse. Use square ones. I found round ones very impractical.

Do you remember from school science that each magnet has a north and a south pole? You need to know which of the magnets’ poles are similar. And it’s easy. Connect them to each other, end to end. When they’re not pushing away from each other you have them in the correct position. Now mark the right side of the magnets with Ns and the other sides with Ss.

What do you need from the hardware store?
- Two 3” pieces of square metal
- Two small flat metal pieces long enough to cover the length of two magnets
- One small flat metal piece the width of your magnet

Firstly you must turn one of your magnets into a giant one. Place the long metal pieces alongside one magnet. This structure should resemble the letter H.

You just turned those two metal rods into a huge magnet. Press it to a heavy metal object. Try lifting it. Fun right?

Now you know how to make a magnet if you ever need a large one for work or for fun. But you’re also going to make it powerless in a short while.

Now for the switch.

Stack your remaining two magnets on top of each other. Their north poles must align. Place the longer flat pieces alongside the magnets with their ends sticking out on one side. The other small magnet is placed across the top of one of your magnets, connecting the other two metal strips.

This is now another powerful magnet, but we’ll call this the switch.

Place the switch on top of your huge H-magnet with its magnet’s polarities opposite to your switch’s.

In school, you probably also learned that north and south poles attract. Your switch’s metal ‘legs’ will stick to the huge magnet.

Now try and pick something up with it. Why can’t you? Your permanent magnet is not so permanent anymore.

You just collapsed the magnetic field by the unique alignment of the different poles.

Want to use the magnet again? Simply turn your switch 180° while the bottom part stays put. You’ll see you actually doubled the magnet’s power by adding the switch in this position.

It simply has to be turned in the right direction.

Ready to baffle your friends with some science?

Via Magnetic Games


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