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Eddy Currents: Aluminum Pendulum in a Magnetic Field

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Here are a couple demonstrations of eddy currents and induction I have this aluminum paddle and you know that aluminum is not naturally magnetic. If I stick it up next to my big horse shoe magnet it just falls off. Alright I'm going to suspend it from this rod and I'm going to swing it just like a pendulum, okay nothing unusual about that. I put the magnet right there, so that the paddle can swing through the magnetic field it's a very strong magnetic field and it comes right to a holt. What's happening is that the magnetic field of the horseshoe magnet is inducing a current in this paddle. These currents produce magnetic fields of their own and according to Lenz's law the magnetic field produced will be such as to oppose the affect that produced it. The opposition is to try to as the paddle goes in to the magnetic field to push it out again so we get a force opposing the motion and that's why we get to a stop so quickly now we can do things to induce the effect of what are called eddy currents. We can simply cut slots in the paddle and now it just swings through as if nothing happened alright so because of the slots we do still get eddy currents but they're much smaller, you can't have bigger currents throughout the paddle. Try this paddle right here then we can have big currents through it again we can have different pathways for current see, and that also comes to a stop quickly.


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