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How to Optimize a simple Electromagnet

  1. Apr 28, 2016 #1
    My goal is to make an electromagnet that delivers 100mT magnetic field on one end of the iron. The iron core has a diameter 2.0mm and length 0.1m. I am using a copper wire that can carry 2.3A of current, and I am using a DC power supply.
    I have been able to create a 100mT magnetic field on the end of the iron, but I now I need the 100mT magnetic field to be present 1-3 mm away from the end of the electromagnet.
    I do know the formulas and have calculated the different variable for the magnetic field using:
    B(end) = (kuNI)/2L..
    What should I do to optimize the magnetic field:
    1. Cut the iron in half and combine the two pieces to make a stronger core?
    2. Simply wrap more coils around iron? (I heard this may cause faster wire burning)
  2. jcsd
  3. Apr 28, 2016 #2


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    Staff: Mentor

    Welcome to the PF.

    Can you say what the field is for? How uniform does it need to be in the volume that is 1-3mm away from one end of the bar?

    One way to make it stronger is to bend your bar around so the two ends face each other and are about 5mm apart. Can you do this?
  4. Apr 28, 2016 #3
    I am just making this for class, but those were the specs I was given to make.
    I do not think I will be able to bend the bar ( I assume you are talking about a horseshoe electromagnet).
    My options are to cut the iron core in half and line it up side by side, or keep turning the coils around the iron.
    Do you think that would be the best approach?
  5. Apr 28, 2016 #4

    jim hardy

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    Science Advisor
    Gold Member

    Berkeman had the right idea...... reduce air gap and encourage flux to stay in it.

    Can you surround your iron bar with a magnetic path ?


    6 inches is .15 meter
    clamp your core and epoxy it in place at the fixed end . A small block of wood drilled to 3/32" will give you more glueing surface.
    Now you have an adjustable air gap which gives you control of the the dominant L in your flux equation
  6. May 2, 2016 #5
    You have to find out the optimum discharge current to get the best battery life. Also, you have to optimize your magnet design, especially the coil, to match your battery.
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