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Force beteween two bar magnets

  1. May 28, 2008 #1
    Hi there. I got two questions for you:

    1- How can I calculate the force of attraction in Newton of two bar magnets of about 5 cm long and 2 cm wide separated by a few centimentres?

    2- If I want to reduce near to nothing the attraction of these two magnet (whil still kept at the same distance), what would be the best material to put in between and how big the piece of material would need to be?
  2. jcsd
  3. Jun 6, 2008 #2
    Hi, I am not 100% sure about this but I think you would need to know a lot more about the magnets than just the lenght to determine the force of attraction.
    For your second question I am pretty sure that magnetic attraction can't be cancelled out no matter what you put in between the magnets.
    Sorry if that didn't really help you.
  4. Jun 10, 2008 #3

    As to your first question, Nerd is right. Magnets come in many different strengths, and that strength does not depend on it's physical size.

    As to your second question, there are metals that you can use to block out the force of attraction or repulsion between 2 magnets, however the metal itself is attracted to magnets, so I'm not sure if it would do what you're hoping to do. It's called mu metal. It doesn't "block" magnetic fields, it just redirects it somewhere else. But if you were to place a strip of mu metal over one of the magnets, and a second strip over the other magnet, you could effectively reduce or even completely cancel out the attraction/repulsion between the two magnets (depending on the strength of the magnets, type of mu metal used, distance between the magnets, ect.). There are also other, cheaper metals that do very much the same thing, and are capable of being cut and shaped. Mu metal has to be custom made, because once you cut it, it loses a lot of it's properties. Just do your research.

    I hope this helped.
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