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Old Aug 24th 2018, 03:02 AM   #1
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Inductive effect

If you move the north pole of a magnet towards a coil of wire in a closed circuit, a current will flow in the wire which will result in a magnetic field in opposition to the north pole ie. another north pole in the coil.
Alternatively if you move the south pole of a magnet away from the coil a current will flow in the wire which will result in a magnetic field attempting to restrain the weakening south pole ie. a north pole.

My question is what would happen if you moved the north pole of a magnet towards the coil while simultaneously moving the south pole of another magnet away from the coil. Would current flow in the coil and develop a magnetic field?
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Old Aug 24th 2018, 05:20 AM   #2
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Originally Posted by p75213 View Post
My question is what would happen if you moved the north pole of a magnet towards the coil while simultaneously moving the south pole of another magnet away from the coil. Would current flow in the coil and develop a magnetic field?
So you are moving a N pole towards the coil ,which will induce a N pole in the coil

And you are moving a S pole away (from the same end of the coil) which will also induce a N pole in the coil ...

The coil will see the magnetic flux changing twice as fast and the induced magnetism will be double ....

If a N pole was moving towards one end of the coil , and a S pole away from the other end of the coil then the coil would see no net change in magnetic force , no induced current ...no force on the magnets ....I think ....
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Old Aug 24th 2018, 05:35 AM   #3
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The south pole is moving away from the opposite end of the coil.
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Old Aug 24th 2018, 08:52 AM   #4
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Originally Posted by p75213 View Post
The south pole is moving away from the opposite end of the coil.
In that case the coil sees no changing magnetic field , no current induced in the coil so the magnets would experience no force from the coil ....

Or to put it another way , at one end the N pole moving towards the coil wants the electrons to move one way around the coil ...but at the other end the S pole moving away wants to move the electrons the other way ... so the electrons don't move at all!

It's the same effect if 2 N poles (or 2 S poles ) both try to approach each end , or both try to move away ....no force on the magnets from the coil , it's as if the coil is not there.
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