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Electromagnet won't work

  1. May 27, 2016 #1
    In my adventures through my attempt at a home laboratory i decided i would try to play with electricity a bit more.

    I took an iron cylinder 1 inch diameter 6 inch length and wrapped about 4 meters of 1mm copper wire around it with a small length hanging off each side.

    ImageUploadedByPhysics Forums1464331677.588642.jpg

    To my understanding when i touch each side to a power source the result would be the magnetized iron, this was not the case. What did i do wrong?
     
  2. jcsd
  3. May 27, 2016 #2

    DrClaude

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    Is the copper wire insulated?
     
  4. May 27, 2016 #3
    No its not
     
  5. May 27, 2016 #4
    I got the copper wire from an old T.V. Where it was used in an inductor
     
  6. May 27, 2016 #5

    DrClaude

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    There you go, you just built a big, straight wire. :smile:

    The make an electromagnet, the current has to flow in a spiral around the core. You need insulated wire for that.

    If it was used in an inductor, then it should be insulated. It is possible that the insulation is broken (or melted), making short circuits.
     
  7. May 27, 2016 #6
    Ok i get it so i could say wrap the wire in electrical tape and then coil it and it should work
     
  8. May 27, 2016 #7

    jtbell

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    If you still use non-insulated wire, make sure the individual turns don't touch each other.
     
  9. May 27, 2016 #8

    DrClaude

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    You need also to put some tape around the iron core to isolate it.
     
  10. May 27, 2016 #9

    sophiecentaur

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    If it was used in an inductor then it must be ok for the job. There must either be an open circuit (is there any way for you to know current is actually flowing?) or a flat battery or a short between the ends of the coil.
    With the amount of current that cell could probably supply, you could expect to see small sparks when you brush one of the contacts with one end of the wire.
     
  11. May 27, 2016 #10

    sophiecentaur

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    Thinking about this some more I guess that you just cut the wire and didn't strip the clear laquer insulation from the ends and there is no electrical contact. Try scraping gently with a knife or with emery paper. Alternatively, applying a hot soldering iron with solder may well dissolve the laquer and give it good 'tinned' ends for a good contact. I am sure that will sort out your prob.
     
  12. May 27, 2016 #11

    davenn

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    well actually if it came from a coil in an old TV ... it WILL be insulated, else it wouldn't have worked for that coil

    What you haven't done is scrape the enamel insulation of the ends of the wire
    so use a razor blade, craft knife etc and scrape the almost clear enamel insulation of around an inch off each end
    THEN it will have proper connection to the battery


    cheers
    Dave

    PS .... I didn't read sophie's post fully .... in full agreement
     
  13. May 28, 2016 #12
    It works!! Thank you all
     
  14. May 28, 2016 #13

    davenn

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    well done :smile:

    scraping the ends of the wire did the trick, I assume ?


    cheers
    Dave
     
  15. May 28, 2016 #14

    sophiecentaur

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    It really is unfair that they use so much 'gold' coloured laquer. Many other colours are available and everyone would spot a red or purple wire isn't plain copper.
     
  16. May 28, 2016 #15

    davenn

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    so true
    ... a nice trap for young players :wink:
     
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