Today we played with electromagnets.  I had already set up a snap circuits demo with a solenoid and showed that when the current was turned on the iron core was sucked into the solenoid.  Then I had the students make their own solenoid with wire, a large iron nail and various batteries.  I challenged them to make a better solenoid – who can pick up the most paper clips with their electromagnet.  We talked about how more turns would make it stronger or more current (more batteries).  I also have  a Texas Instrument sensor that connects to my iPad via bluetooth and it can measure the magnetic field directly.  The largest reading we got was around 0.9mT.

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The students also made little coils that will keep spinning when placed over a magent. These are a lot of fun and the students always enjoy making these.  Its helps to have strong magnets, but you can make it work with most regular magnets and a bit of magnet wire.

One student made a large coil and hooked it up to an ammeter, but NO BATTERIES.  Obviously no current was going through the coil, but when you move a magnet in and out of the coil it induces a current in the circuit.  We were able to get close to 1mA by dropping neodynium magnets through the coil.

Speaking of neodynium magnets… I want to do this demo so bad.

 

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