pleaaaase help me to understand lenz'slaw

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#1
I really can't get it or let it into my mind I know that it's about the current opposing the change but i still can't fully be sure of it...and the more I read about it the more I realise I don't get it please if you have a good link to a site which explains it in details or if you are good at physics then help me pm me or whatever
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15 years ago
#2
im a bit rusty on physics a level i last did it last july but i got an A. just remind me, is that the one about electromagnetic induction?
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15 years ago
#3
http://www.launc.tased.edu.au/online/sciences/physics/Lenz's.html
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15 years ago
#4
(Original post by habosh)
I really can't get it or let it into my mind I know that it's about the current opposing the change but i still can't fully be sure of it...and the more I read about it the more I realise I don't get it please if you have a good link to a site which explains it in details or if you are good at physics then help me pm me or whatever
Opps ..
Ok, let consider a magnet S-N is moving to a coil (north pole is nearer to the coil). So North pole is moving to 1 end, this end will be "..." to oppose the North pole's move? So this end becomes North pole.

When that magnet S-N is moving far away from the coil (still north pole is nearer). So that end of the coil wants to keep North pole not moving far away, it must be South pole in this case.

Hope it;s ok.
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#5
(Original post by BCHL85)
Opps ..
Ok, let consider a magnet S-N is moving to a coil (north pole is nearer to the coil). So North pole is moving to 1 end, this end will be "..." to oppose the North pole's move? So this end becomes North pole.

When that magnet S-N is moving far away from the coil (still north pole is nearer). So that end of the coil wants to keep North pole not moving far away, it must be South pole in this case.

Hope it;s ok.
that one i get it thanx though,but the thing that i don't get is when we have a swinging ring like a pendulum through a magnetic feild or worse,when we have a metal plate
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#6
(Original post by magiccarpet)
im a bit rusty on physics a level i last did it last july but i got an A. just remind me, is that the one about electromagnetic induction?
yep it is
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15 years ago
#7
(Original post by habosh)
that one i get it thanx though,but the thing that i don't get is when we have a swinging ring like a pendulum through a magnetic feild or worse,when we have a metal plate
In this case, there is a induced current(flow of electrons) in the ring or the metal plate. Use right hand rule to find the direction of the current.
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#8
(Original post by BCHL85)
In this case, there is a induced current(flow of electrons) in the ring or the metal plate. Use right hand rule to file the direction of the current.
that is what i don't get,how to do so,I know how to use right hand rule but how once it's clockwise and the othertimes it's anti
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15 years ago
#9
(Original post by habosh)
that is what i don't get,how to do so,I know how to use right hand rule but how once it's clockwise and the othertimes it's anti
Arh, right
Open your right hand. Now let the magnetic field goes into your hand. Let your thumb shows the direction of movement of the ring/metal plate. And the current is found by the direction from your wrist to your fingers.
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#10
(Original post by BCHL85)
Arh, right
Open your right hand. Now let the magnetic field goes into your hand. Let your thumb shows the direction of movement of the ring/metal plate. And the current is found by the direction from your wrist to your fingers.
I'm so sorry hun but I still can get it if that was the case then the current would be in the same direction of the magnetic feild but infact it should oppose it right??
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15 years ago
#11
(Original post by habosh)
I'm so sorry hun but I still can get it if that was the case then the current would be in the same direction of the magnetic feild but infact it should oppose it right??
Oh no! You misunderstood. The current can never be in the same direction of magnetic field. It's always perpendicular to the magnetic field. Let open your right hand. If the magnectic field is into your hand, and the swing goes to the right, so the current will be downwards. (it's induced current).
After that, you use the left hand rule to find the force acting on the the ring/metal plate (it must be oppse the moving direction). D
Don't mixed induced current in moving wire in magnetic field with a wire carrying a current in magnetic field
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#12
(Original post by BCHL85)
Oh no! You misunderstood. The current can never be in the same direction of magnetic field. It's always perpendicular to the magnetic field. Let open your right hand. If the magnectic field is into your hand, and the swing goes to the right, so the current will be downwards. (it's induced current).
After that, you use the left hand rule to find the force acting on the the ring/metal plate (it must be oppse the moving direction). D
Don't mixed induced current in moving wire in magnetic field with a wire carrying a current in magnetic field
thanx alot...now I get it...that is like saving my life...
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15 years ago
#13
(Original post by habosh)
thanx alot...now I get it...that is like saving my life...
np. It's good for me to revise it too
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