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Electro Magnet question

  1. Aug 25, 2005 #1
    I cant find any sort of charts for the stregths of different metals that i could use as the core for my Electro Magnet(EM).

    some plans for a E.M. would be kinda cool to see too if anybody has any.

    (also, this is my first post on this site and i am really excited because ive been lookin for a quality site like this for a long time. and i know that i will be asking a lot of questions because i still have a lot to learn.
  2. jcsd
  3. Aug 25, 2005 #2


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    Homework Helper

    You do mean "magnetically strong", not tensile strength, right?
    It all depends on how much you want to pay ...
    and how much machining you plan to do -
    I won't let you grind magnetic steel on MY grinder!

    You'll need to decide whether you want high maximum field,
    (the extreme coordinate on the "hysteresis curve/loop")
    or whether you want good linearity and control
    (and low residual field when "off", the hysteresis intercept).

    google saturation, hysteresis curve, residual - reply back if not satisfied.
  4. Aug 25, 2005 #3


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    Here is a helpful sight on what you want to know. Hyperphysics is a absolutely splendiferous site, and you will probably be directed to it many times.

    And this is what you specifically asked for, a table of relative
    permeabilities for various paramagnetic, diamagnetic, and ferromagnetic core materials: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html#c2

    An iron nail with tightly wrapped magnet wire around it works well as a first electromagnet. And later maybe you can work your way up to an NMR! http://www.cis.rit.edu/htbooks/nmr/chap-7/chap-7.htm#7.2

    Before you can start with the construction of an electromagnet, you first need to figure out the following:
    1. What will the core be made of
    2. What magnetic flux density are you trying to achieve
    3. How many turns will be required for this along with
    4. How many amps will be flowing through the wire
    5. How big will the wire have to be to handle the current
    6. How much surface area will you have for cooling the coil
    7. How big will the electromagnet be due to the above
    8. What voltage rating will the insulation of the wire have to withstand
    9. What will be the inductance of the electromagnet
    10. Obtain the core, wire, bobbin (form for the winding)
    11. Wind the coil
    12. Test the electromagnet

    Or you could just do it, and test the strength.

    Neodymium magnets are worth the money, I have 25 in my bedroom and they are awesome. You can easily amaze your friends, family, and yourself over and over again. But with power comes a price. They shatter easily, and its likely if you drop one more than once it will break up into pieces. It hurts like hell if flesh gets in between two magnets, afterwards there is a bruise. And don't bring them near any sharp objects, what am I saying? Its all in the handbook you get if you buy it.


    From powerlabs, stuff you'll never do, but its really fun to read about.
    Last edited: Aug 25, 2005
  5. Aug 27, 2005 #4
    ok thuis stuff is good and helpful but do any of your guys have or have links for any EMs
  6. Aug 28, 2005 #5


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    What? I gave you a whole bunch!

    This handsized magnet can lift 200 pounds!!:

    And always STAY SAFE when you're working with more than a few amps. Keep one hand in your pocket at all times when touching something metallic. Electrocution is one of the fastest ways to go, and you don't even see it coming. If you don't die, you end up with terrible burns and/or bruises.

    And what do you mean by "links for EMs?"

    Links on how they work? actual ones? famous ones? interesting ones?
    Last edited: Aug 28, 2005
  7. Aug 30, 2005 #6
    when i said links i meant how to make em(but not the science behind it, the plans and designs) and maybe some stuff on power sources, both ac and dc.

    and thank you very much for the links so far
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