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B Small powerful electro magnet

  1. Sep 16, 2016 #1
    Hello, i need a small electro magnet with it's dimension not bigger than 8 millimetre (0,31 inch) in diameter with a length under 10 millimetre (0,39 inch).

    I want it to be as powerful as possible, where do i find such magnets? And how should i make my own?

    How powerful is it possible to make it?

    Could i just use a big battery and waste much electricity to the small magnet, in order to make it really strong?
  2. jcsd
  3. Sep 16, 2016 #2


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    welcome to PF :smile:

    for electro magnets, small and powerful is pretty much a contradiction in terms

    you can have small or you can have powerful but not both

    so what is your application .... ie. what are you trying to achieve ?

  4. Sep 16, 2016 #3
    Thanks :)
    I try to make a force that will catch a metal pipe about 8cm (3 inch) away. I turn on the electro magnet, and the pipe will smash into it.

    But it have to be small and pretty powerful... Is it possible to stream much electricity to a very small magnet, in order to make it as strong as a bigger with less electricity? Or is it any other solution possible for me?
  5. Sep 17, 2016 #4
    Superconducting wire will carry much larger currents than normal copper wire but if it's tightly wound the size of the current will be limited by the magnetic field around the wire. The best approach would be to magnetise a small puck of superconducting material like YBCO. Fields as high as 17 tesla have been achieved.
  6. Sep 17, 2016 #5
    A small superconducting puck (diameter approximately 25 mm) with a field of 17 tesla would not be easy to make. The puck has to be put inside a large electromagnet capable of generating this field and then cooled to a temperature of about 29 K or less to freeze the field lines in. The puck cannot be made of just YBCO because the field lines would blow the puck apart. The YBCO would have to be strengthened somehow by being impregnated with some type of resin. You would have to have a well resourced laboratory available to you!
    Last edited: Sep 17, 2016
  7. Sep 21, 2016 #6
    If you put in more electricity into the electromagnet you most likely will burn the coil inside of it
  8. Sep 21, 2016 #7


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    I'm not sure about "smash", but one way to operate a coil is to give it excessive current but for only a brief duration, so that before the wire begins to glow red the magnet has already performed its task and can then be given plenty of time to cool down. The enemy of electromagnets is heat.

    What are the dimensions of your metal pipe? Is it steel? Is it stationary? Is it resting on a smooth, slippery surface? How much space is available for the electromagnet?
  9. Sep 21, 2016 #8


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    I don't think it's possible to do what you want safely or economically. It's easy to build an electromagnet with a battery and some wire and an iron core, and you can pick up paperclips and small pieces of metal at very short distances (almost touching). But if you want to scale it up to high field strength, you will have to scale up the size as well. Small wires can't handle the current required without overheating, and small insulators can't handle much voltage before arcing.
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