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Electromagnets and an induced magnetic field in aluminuium plates

  1. Mar 5, 2009 #1
    I am trying to conduct an investigation based on the set up of a set of copper coils with AC ran through them to make them an electromagnet. Held above them inplace is an aluminium plate. I know that the changing magnetic field induces a current in the aluminium plate, which induces a voltage and then a magnetic field which is out of phase with the electromagnet, and so an oposing force is made. I am measuring the force by having a sensitive set of scales under the coil which measures the change in force on the coil.

    However i am trying to investigate the effects of changing the electromagnet

    I have already tried
    -different diameter of wire.
    -Differnt radius of the coils
    -Different number of coils.
    -Changing the current through the coils.

    I have already discovered (i think) that it is a squared relationship for increasing the current and force.

    However is there an equation for this?

    Also, what kind of relationship should i expect with the other factors and why?

    How exactly would i calculate the force that results in the copper coils being pushed in to the scales? Measuring the change in weight only really gives me a sort of qualatative answer.

    any help would be much appreciated.
  2. jcsd
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