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Electric and Magnetic Field Relationship at the Surface of a Wire

  1. Oct 30, 2012 #1
    1. The problem statement, all variables and given/known data
    A 0.60 m long circular tungsten wire with a radius of 0.05 m is connected to a DC power source resulting in a current of 0.65 A in the wire. Calculate the magnitude of the electric to magnetic field ratio at the surface of the wire. The resistivity of tungsten is 5.6 · 10-8 Ωm


    2. Relevant equations

    B(inside a wire) = μ*I/2∏R^2 * r where R = the radius of the wire and r = location within the wire radius... and since it is at the surface r=R.

    Is that how you calculate the B field?

    Also, I have no idea how to calculate the E field at the surface. I don't know how to relate resistivity into any of this. And does the I'm assuming the fact that it is a circle affects something but I don't know what.

    I'm really lost on this problem so any response will be greatly appreciated!


    3. The attempt at a solution
     
  2. jcsd
  3. Oct 30, 2012 #2

    TSny

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    Good on the B field except is r squared? For E, you can try applying Ohm's law to a short segment of the wire.
     
  4. Oct 30, 2012 #3
    Well since the r=R R/R^2 should reduce down to just R correct? and do you mind expanding on that? I really don't know how to do that :/
     
  5. Oct 30, 2012 #4
    Nevermind I got it! thanks though
     
  6. Oct 30, 2012 #5

    TSny

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    Oh, you were correct on the R factor. Good.
     
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