Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

ElectroMagnet Help Please

  1. May 25, 2013 #1
    hello everyone, I've spent countless hours and a ton of money on trying to get this work. What I am making is a electromagnet with a decent amount of strength, but mine doesn't work at ALL.
    I am using copper megnetic wire and have tried both 9V AND AA. I've included pictures of both my coil and my type of wire, If there is anything you think I'm doing wrong I would LOVE to know, Thank you all!

    Attached Files:

  2. jcsd
  3. May 25, 2013 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF;
    What do you mean by "a decent amount of strength"?
  4. May 25, 2013 #3
    You probably have shorted the coil. From the picture it looks as if your have tinned your wire to the core.

    Do you have an ohm meter?
  5. May 25, 2013 #4
    I want to pick up be able to hold a small metal ball with it

    I want to pick up be able to hold a small metal ball with it
  6. May 25, 2013 #5
    I dont

    I don't actually, is there a way I can avoid this?
  7. May 25, 2013 #6


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    that really doesnt make sense .... its obvious to see that the wire still has the enamel coating on it

    Kyle ... you do realise you have to scrape off a little bit of the enamel coating at the ends of the wire so that you get an electrical contact to the battery ?

  8. May 25, 2013 #7
    I know, i used to have a load (light) connected in the circuit and it worked, the electricity is flowing through i just dont know my problem
  9. May 25, 2013 #8
    I will be able to get a multimeter later today, is there anything i should look for?
  10. May 25, 2013 #9
    Yeah, continuity. Turn the meters to ohms Ω

    Not sure what kind of meter you have, if you have several ranges for Ω go to something near 200

    Your going to put one lead on the core itself. Just pick a spot that isn't covered by wire. Put the other lead on the wire you have been hooking to the positive side of the battery.

    Repeat for the wire on the negitive side of the battery.

    Watch your meter. Are you getting any reading from either wire?
  11. May 25, 2013 #10
    Chisels are made from hard steel.
    Try a nail or a low cost steel bolt.
    Scrape the wire ends where you connect to the battery. A knife works OK if you are careful.
    The ohms scale on you meter probably won't tell you anything.
  12. May 25, 2013 #11
    Also, it appears you have only one layer of wire. Try winding several layers over a shorter length of a bolt.
    More battery power will also help. A single 9v battery can't provide very much current.
  13. May 25, 2013 #12

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    How heavy is the ball?
    Have you made sure that the ball can be picked up by a permanent magnet?
    Will your electromagnet pick up anything? Paperclip? Iron filings?
    Does the battery warm up much when it's in use?

    The strength of the electromagnet depends on the current through it, the number of turns, the diameter, and the core material. Generally the relationships are quite complicated so when you are starting out it is a good idea to keep the geometry as simple as you can. It is possible to work out rules of thumb from there (and looking them up of course).

    Have you been looking up the theory of electromagnets?
    Have you looked through the many similar questions on PF?
    Have you tried following one of the many demonstrations on youtube?

    A multimeter is an essential tool for messing about with electronics - you must get hold of one.
    The Ohms scale can tell you stuff like if all the turns in your coil are conducting or if there is a short that bypasses a lot of them. A simple continuity tester (battery+wires+light-bulb) ca be used to investigate if there is a short to the core though.
    You can also investigate the current through the coil and the voltage across it.

    You do want an iron core - and I'd keep a small additional load in series too.
    It may be possible to figure out what your coils should be capable of if we knew the dimensions.
    Looks like about the diameter of an AA battery, on a hardened steel core, quite a small gauge I guess I could count the turns...
  14. May 25, 2013 #13

    jim hardy

    User Avatar
    Science Advisor
    Gold Member

    it needn't be fancy. I use the $10 black analog one from Wal-Mart.
  15. Jun 2, 2013 #14

    Since you've been working on this for a while I would check the battery to see if it is still alive. You would set your meter to the smallest D.C. Volts scale that is still larger than your battery's normal working voltage. Put the red lead of the meter on the + (positive) terminal of the battery, and the black lead of the meter on the - (negative) terminal of the battery. The volt meter takes very little current from the battery, so if for example you have a 9 volt battery and it only reads 7 or 8 volts on your meter, it is basically a goner and it's time to buy a replacement.

    Good luck!
  16. Jun 2, 2013 #15
    How many windings do you have? When I made a levitator that could levitate a small metal ball, it required something more than 1000 (a thousand) windings.

    PS. Well not "required" per se, but thats how many we used, and it wasn't a super-crazy magnet.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook