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Focusing electromegnetic energy short distances

  1. Nov 11, 2011 #1
    I just want to be up front with all of you, I am not a physics guy. I am trying to accomplish a goal. I need to focus a two inch electromagnet's energy into a quarter inch diameter area, four inches away from the magnet. Can this be done and how? Please explain in laymens terms, drawings would be nice. Thank you in advance for your time and thoughts. I must say, I am very impressed with the caliber of people on this site. Its good to know there are still thinkers out there.


  2. jcsd
  3. Nov 11, 2011 #2
    For clarity, what do you mean by focus the energy 4 inches away? Do you mean that you want 4 inches of space adjacent to the magnet void of magnetic field?
  4. Nov 11, 2011 #3
    I believe that is correct. I am wanting to focus all of a 140 lb electromagnets pulling force into a quarter inch diameter metalic object and make it travel upward through four inches of empty space.


  5. Nov 11, 2011 #4
    What you're up against is the fact the field strength drops off according to the inverse square law: double the distance of a thing from the magnet and the field is only one forth as strong. 4 inches is a very long distance in magnetic field terms. The magnet might support a weight of 140 pounds if, and only if, that 140 pounds is in direct contact with the magnet. At 4 inches the same magnet could easily be insufficient for your purposes. The field spreads out more and more the further you are from the magnet and their is no real way to keep it "focused", no such thing as a magnetic "lens".

    If it's not working as you have it now, I think you have only three options:

    1.) A more powerful magnet

    2.) Shortening the distance

    3.) A lighter object
  6. Nov 12, 2011 #5
    Is there a material that will reflect, repel or condense an electromagnets energy. Unfortunately we have to stick to the size and distance we talked about earlier. Luckily I dont know the law you are speaking of so, I'm gonna be like Wiley Cyote and gravity. So far I've defied gravity a few times, not knowing I couldn't do something and did it anyway. If you all could help me think outside the box for a bit it would be great. Thanks for the input so far.


  7. Nov 12, 2011 #6
    Inverse cube law...it's a dipole field. So doubling the distance leads to the field being 1/8th as strong. (when you're far enough away that the geometry of the magnet isn't important)

    Jheistand, there's little anyone can do without a better idea of what you're ultimately trying to achieve. You're asking for out of the box thinking, but you've only given a vague and rather confused description of a very specific problem that may well be completely unnecessary. It's not even meaningful to talk about manipulating the "energy" of an electromagnet in the way you describe.

    You can guide the field somewhat with materials of high permeability, such as soft iron. This can allow you to, for example, suspend a chain of nails or paperclips from a magnet, stretching to distances where the magnet could not pick them up directly.
  8. Nov 12, 2011 #7
    I don't know how else to discribe what I'm wanting to accomplish. Just imagine that I had a piece of steel the size of a watch battery sitting on a table that weighed 100 pounds and I needed to lift it 4 inches off of the table, how could this be accomplished within the dimensions I described above. Can you create a funnel made of reflective non energy absorbing material that will focus the energy enough to raise that 100 lb watch battery four inches at which point it would hit a solid mass, housing, magnet, lens, something. I am somewhat of an inventor. I can't completely disclose what I'm doing, but that scenerio will work. I cant imagine that the energy of a magnet can't be harnessed and focused at short distances. If the force spreads over space, why can't you keep it condensed?


  9. Nov 12, 2011 #8
    IT IS possible to concentrate a magnetic field...that's what the iron core in electromagnets are for!...but you keep saying that you want a 4-inch gap
  10. Nov 12, 2011 #9

    Unfortunately for the OP, though, he's up against a worse problem than I thought.
  11. Nov 13, 2011 #10
    Ok so if I made a 4 inch long funnel made of iron with a 3/8s hole on the bottom and 2 inch hole at the top, then attached the top of the funnel to the bottom of the 2 inch magnet and set the 3/8 bottom over the 100 lb watch battery would that concentrate enough energy to pull it up th the bottom of the magnet . If not what material could I use. We're getting closer!


  12. Nov 13, 2011 #11
    A solid cone-shaped object of a high-permeability material in the proper position can concentrate a magnetic field, but there's a limit to the achievable magnetization that depends on the material...when it reaches saturation, it won't concentrate the field any further. And being a solid object, you're not going to be lifting anything through the 4 inches it spans, you may as well just move the electromagnet.

    You can't very well ask us to help you think outside of the box you put us in, can you?

    Again, it's not meaningful to talk about the "focusing" the "energy of a magnet". It's also not meaningful to talk about the force being "condensed".

    No material will make that work.
  13. Nov 13, 2011 #12
    This "funnel" is going to completely block your 4 inch gap. If the 4 inch gap doesn't need to be open in the first place, you can simply make a solenoid. The 100lb battery, if it's only 1/4 inch diameter, must be in the form of a rod, no? You can make an empty coil of wire, have the upper end of the battery/rod sticking a little way into it, then when you energize the magnet the rod will be sucked into the coil (solenoid). It will try to take up a position where the middle of the rod (the center of its length) is lined up with the middle of the solenoid. Depending on the length of the rod, you might lift it considerably more than 4 inches.
  14. Nov 14, 2011 #13
    The funnel would be open from top to bottom creating the four inch gap. It would have a two inch hole on top to fit below the magnet and a 3/8s hole on bottom to fit over the quarter inch diameter battery. It would look just like the funnel you use to put in motor oil. My email is heistandsalarm@insightbb.com if you would like me to send a drawing.


  15. Nov 14, 2011 #14
    A hollow cone or funnel would be a better discription.
  16. Nov 14, 2011 #15
    Thank you fellows for staying engaged in this discussion. I aprreciate your time and patience.
  17. Nov 14, 2011 #16
    Not to be rude, but you won't be very successful as an inventor unless you understand a little bit of physics. I recommend working through a college-level introductory textbook on physics. Magnets create magnetic fields, which interact with magnetic materials. Static magnets do not shoot out energy or condense. Fields are not arrows that shoot through space and can be focused like light. If you want stronger magnetic fields at a certain point in free space, you have to use more magnets or stronger magnets, or specially shaped cores. The photo below of part of a particle accelerator may give you some idea on how to "focus" magnetic field lines.

    Last edited: Nov 14, 2011
  18. Nov 15, 2011 #17
    Dear sir, not trying to be rude on this end either, however I want to accomplish a goal. I dont care how I can't do something. What I want to know is how I can. This device has to be hand held and able to provide 100 + lbs of lifting force on a 1/4 inch diameter object and lift if 4 inches off of a surface. I had ideas on how to get it done, to maybe jog some thoughts of ways to accomplish this goal and all I'm hearing is can't, can't, can't. I believe anything can be achieved with the right mind focused in the right direction. I don't have any knowledge in this field nor do I have time to study physics, however this is your trade, that is why I came onto this forum. I have learned as a small business owner that you don't have to know everything, you just have to know the right people who do. With your minds and my idea, I believe that we can accomplish this goal. I know that there are certain physic's laws that everyone abides by, however I also know that throughout history we have evolved and pushed past boundries. With the inernet and the information we can share now, there should be new break throughs happening all over, people with ideas and people with the skills to overcome obstacles uniting and creating something to get this poor country out of it's rut. Sorry I get a little passionate sometimes. I have invented an item recently, started using it, got a patent and won Kentucky's Bucks for Bright Ideas contest for inventors this year and I know nothing about physics. If you are willing to listen to my stupid ideas and help me overcome some obstacles post here or email me @ heistandsalarm@insightbb.com for a more detailed description of what I'm trying to accomplish.
  19. Nov 15, 2011 #18
    The two are inextricably related. Your proposed hollow funnel won't do what you hope.

    It can't be done with the methods you have restricted us to considering...you didn't ask for a way to lift a 0.25" object by 4 inches, you asked for a way to "focus the energy" from a 2 inch electromagnet down to a point 0.25" wide and 4 inches away. This is a limitation you imposed, not us...what I've been trying to point out is that you may be attacking the problem from the wrong direction, and would be more likely to get an answer by basing your questions around what you want to achieve rather than on this particular means of achieving it.

    So you don't want to put in the effort to learning how to design this thing, but you expect help to be donated without any cost to you, which you will then profit from at our expense?

    If you really want some generous soul to give you something to sell, the least you can do is approach people with a better attitude and less obfuscation about what you're trying to do.
  20. Nov 15, 2011 #19
    I think that anyone who helps me achieve the result I am looking for absolutely deserves compensation, we simply never got that far. Matter of fact I have a small grant to do just that, however I didn't want everyone to know exactly what I'm doing and I was waiting for someone to tell me we can accomplish this task, so we could go offline and discuss it further. The 2" electromagnet would be a cost effective way to keep under budget if it were able to be used. Ive got to focus on cost so consumers can afford to buy the product. Weight, size and cost are my biggest hurdles. If anyone besides CJames can help please contact me by email or phone (270) 454-3396. Mr CJames you know what they say about the word assume (*** u me) dont you?


  21. Nov 15, 2011 #20
    Make a solenoid, as I suggested. If you don't know how a solenoid works ask someone you know who does car mechanics: there's a solenoid in every car. I made one myself a few years back, just to play with, from standard enamel coated wire, a steel rod, and a D cell flashlight battery. There's not much to it. The principle and the construction are simple.
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