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# Electromag. Induction watch

1. I am quite confused about a concept. Suppose that a magnet is entering a conducting coil (north pointing in). We know that the current induced will be in a certain direction in order to oppose the magnetic field of the magnet. However, if we have south pointing inwards, will the current induced be in the same direction? If so, why?
2. Use fleming's right hand rule. I think the current goes in the opposite direction.
3. isnt this lenz law ?
4. if the magnet's south is pointing the coil, then the coil's end facing the magnet will also become south(to oppose motion) and hence current flows in the oppsite dirsction
5. (Original post by Wicketer)
I am quite confused about a concept. Suppose that a magnet is entering a conducting coil (north pointing in). We know that the current induced will be in a certain direction in order to oppose the magnetic field of the magnet. However, if we have south pointing inwards, will the current induced be in the same direction? If so, why?
Just to echo what the others have said.
If you use a S pole the current will be in the opposite direction. This is Lenz's Law. The induced current always acts in a direction such that it opposes the change in the magnetic flux producing it.
6. (Original post by Stonebridge)
Just to echo what the others have said.
If you use a S pole the current will be in the opposite direction. This is Lenz's Law. The induced current always acts in a direction such that it opposes the change in the magnetic flux producing it.
This isn't explicit in Lenz's law. I'm not sure what you are referring to by "opposite". So if I use a magnet with the south pole moving into the coil, it will induce a current opposite to the direction of a north pole entering the coil?
7. (Original post by Wicketer)
This isn't explicit in Lenz's law. I'm not sure what you are referring to by "opposite". So if I use a magnet with the south pole moving into the coil, it will induce a current opposite to the direction of a north pole entering the coil?
Exactly.
The nearer end of the coil will become a S pole when you move the magnet's S pole nearer to it, and will become a N pole when you move the N pole nearer to it. The direction of the current in the coil determines whether it is N or S. Clockwise = S, anticlockwise = N. (Looking towards the end in question)
8. Lenz's law is basically conservation of energy

the the induced emf tries to oppose the motion of the magnet, either by opposing it when inserted or attracting it when removed.

If it were the other way round then the magnet would be "sucked in", something which requires energy. Without a power supply this scenario is therefore impossible.

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