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# Physics/Van de graff &Magnet

Question
QUESTION: Hi!
I was wondering if you know any experiments with bar magnets and Van de graff that I can try. What would happen if I placed a magnet on the dome and turned on the machine?

ANSWER: Magnetic fields exert forces on moving charges.  The faster the motion across the field lines, the stronger the force.  So if you put a magnet on the dome and turn it on, not much will happen.  I you discharge the generator in a spark, perhaps through a fluorescent light bulb, the magnetic field might do something, but you probably won't see it.  However, the discharge through a wire set by one of the poles of the magnet might have high enough current to cause short-duration forces on the wire.  I'd use a thin wire, maybe even a coil of wire, and see what turned up.  If you're curious to know the polarity of the generator, you can always attach a current meter to it before you turn it on and see, then take the meter off to allow the generator to operate.

---------- FOLLOW-UP ----------

QUESTION: What do mean by the following:  "However, the discharge through a wire set by one of the poles of the magnet might have high enough current to cause short-duration forces on the wire.  I'd use a thin wire, maybe even a coil of wire, and see what turned up." ? Is there a picture I can see to copy the design?

Thank you.

No, no design.  I was just thinking that if you got the north-to-south magnetic field to cross a thin wire and you got a hard spark to jump through it that it would exert a force on the wire.  (The spark making a big current in the wire.)  I'd just connect a thin wire between something round-ish and metal to ground, and let some of it hang loosely near a magnet...preferably offset from one of its poles (not parallel to the magnet).  See what happens.  If you need help interpreting, let me know.

Physics

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#### Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

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