Physics Help Forum Inductive effect

 Electricity and Magnetism Electricity and Magnetism Physics Help Forum

 Aug 24th 2018, 02:02 AM #1 Junior Member   Join Date: Jan 2010 Posts: 29 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?
Aug 24th 2018, 04:20 AM   #2
Senior Member

Join Date: Apr 2017
Posts: 499
 Originally Posted by p75213 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 ....

 Aug 24th 2018, 04:35 AM #3 Junior Member   Join Date: Jan 2010 Posts: 29 The south pole is moving away from the opposite end of the coil.
Aug 24th 2018, 07:52 AM   #4
Senior Member

Join Date: Apr 2017
Posts: 499
 Originally Posted by p75213 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.

 Tags effect, inductive, magnetism

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post purakanui Special and General Relativity 3 Oct 26th 2013 06:10 AM Steve George Quantum Physics 3 May 16th 2012 04:27 PM clockworks204 Electricity and Magnetism 1 Jul 10th 2010 07:42 PM poonam sandhu Electricity and Magnetism 1 Jan 22nd 2010 05:12 AM werehk Light and Optics 1 Aug 17th 2008 05:21 PM