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Electromagnet pull field

  1. Jul 7, 2010 #1
    I was inquiring about how much force will a 1000 lb pull force electromagnet pull at 4-6 inches away from the magnet
  2. jcsd
  3. Jul 8, 2010 #2
    The precise shape and strength of the magnetic field will depend in a complex way on the shape and materials of the magnet.

    There is no way of knowing.
  4. Jul 8, 2010 #3
    it is a 6 inch radius and it is cylinder shaped pulling a 4 inch cylinder shaped object
  5. Jul 8, 2010 #4
    That's science-speak for 'impossibly complicated and impossible to know without doing lots and lots and lots of careful measurements and probably not even then'
  6. Jul 8, 2010 #5
    A quick guesstimation, involving the simply geometric assumptions and properties, I would put the force at 4 and 6 inches at 360 lb and 250 lb respectively. Of course, as already stated, materials, configurations, etc., could be chosen to blow this out of the water.

    Assuming the magnet is a sphere with a 6 inch radius, the 1000 lb force is effective at 6 inches from the magnet. Thus 4 and 6 inches from the magnet becomes 10 and 12 inches respectively. Simplest force law representation is the inverse square law, m/r^2. Since m/r^2 = 1000 where r = 6 at the magnet surface, then m = 3600. Now solve for other r. Note: this is only roughly valid in the units provided, and a slew of other assumptions about geometry and material properties. But probably good enough for many purposes.
  7. Jul 8, 2010 #6
    Yea, my first thought was to attempt a simple 1/r^2 solution but I decided the likely geometry of a magnet would be flat pole pieces. The approximation to a sphere is just too wild for my taste.

    I should imagine this is a ring magnet anyway. The field would be highly localised.
  8. Jul 8, 2010 #7
    Yes, if the magnet is flat, and the 1000 lb pull is at the flat surface, you've blown my calculation out of the water :tongue:
  9. Jul 8, 2010 #8
    the magnet is 6 inch radius flat surface it has a pull force of 1000 lbs kinda shaped like a can and the object it is pulling would be on my first guess a iron core object but i am open to any suggestions i just wanted to have a good idea of how much becuase it cost alot to buy the magnet
  10. Jul 8, 2010 #9


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    I think the best way to answer this question would be to do a measurement. Also, the force will depend on the material in the object being attracted to the magnet.
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