Need help doing force calculations with magnetism (between magnets)

  • #26
jim hardy
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By the way, is there any way for me to upload images from my computer to this forum?
I use MSPaint to save them on my computer as jpg. That way i can draw arrows or type notes on them. Then Upload works great.
Microsoft's "Snipping Tool" is incredibly handy for getting things copied into Paint, but i cant find it in their downloads anymore. It's out there from other sources, though.
 
  • #27
marcusl
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I am very glad that you've found this helpful.
But I was not asking that in my later posts. What I was asking is if I could generate force using by introducing non-linearities or curves in what would otherwise would be a uniform field.
I was trying to point the way through that analysis for you in post #20. I hope someone else will continue from here.
 
  • #28
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Lorentz_Meissner.jpg

Alright, here is the drawing I was trying to bring focus to. (I can't believe I didn't notice the upload button.) Now I realize this probably does create a force but what is it pushing AGAINST in this example as per Newton's third law? Will it push against the superconducting material in the center or will it be pushing against where the field lines are coming from and going to?

Also I realize that other materials can interfere with magnetic fields and seem to block them out. Fro example, I've seen magnets where they attach to a filing cabinet or refrigerator you can see the sticker on the side facing you, usually with an advertisement on it. Flip it around however, it falls like a rock. So what is going on in that case? And would the result depicted above be the same if the superconductive material were replaced with whatever material these stickers are made of?
 
  • #29
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I've seen magnets where they attach to a filing cabinet or refrigerator you can see the sticker on the side facing you, usually with an advertisement on it. Flip it around however, it falls like a rock. So what is going on in that case?
A fridge magnet is an example of a Halbach array. Envision a horseshoe magnet. Both north and south pole faces are in the same direction with very little flux 180° from the pole face direction. Now consider a side-by-side row of horseshoe magnets. Nearly all magnetic flux is on one side, and very little on the other.
 
  • #30
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A fridge magnet is an example of a Halbach array. Envision a horseshoe magnet. Both north and south pole faces are in the same direction with very little flux 180° from the pole face direction. Now consider a side-by-side row of horseshoe magnets. Nearly all magnetic flux is on one side, and very little on the other.
How does that relate to this particular case?

All I'm asking is are there other materials besides superconductors that can deflect magnetic fields the same way the meissner effect does?
 
  • #31
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How does that relate to this particular case?
It doesn't. You had also asked about how refrigerator magnets work, and my answer was to that specific question.
Also I realize that other materials can interfere with magnetic fields and seem to block them out. Fro example, I've seen magnets where they attach to a filing cabinet or refrigerator you can see the sticker on the side facing you, usually with an advertisement on it. Flip it around however, it falls like a rock. So what is going on in that case
All I'm asking is are there other materials besides superconductors that can deflect magnetic fields the same way the meissner effect does?
My understanding is the meissner effect is exclusive to superconductors. A superconductor is rendered nearly perfectly diamagnetic by virtue of the meissner effect, however, a wide range of diamagnetic materials exist.
 

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