I had some neodymium magnets lying around, and some Lego, and I've never actually seen some simple electromagnetic things in action -- you know, the stuff they illustrate in physics books, but it's so basic it's not worth doing a lab on. Kids' science fair stuff, right?
So I build a Lego gadget that turns a wheel, with 6 cylindrical magnets at the rim of the wheel, cylindrical Z axes aligned with the axle of the wheel (magnetic poles alternating N/S/N/S/N/S). Then I hold a little bobbin of magnet wire up close to the spinning magnets and look at the voltage across the coil with an oscillscope.
What do I see?
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Why don't I get a nice almost-sine wave?
d.