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Electric field

  1. Apr 21, 2012 #1
    1. The problem statement, all variables and given/known data
    A uniformly charged wire or radius R1=0.02m runs down the axis of a cylinder of inner radius R2=0.06m. The potential difference between the wire and cylinder is 60 volts. Find the electric field at the surface of the wire.

    2. Relevant equations
    Electric flux=Q/[itex]\epsilon0[/itex]
    Electric flux=integral of E dA
    V=integral of E dr

    3. The attempt at a solution
    Q/[itex]\epsilon0[/itex]=E(2pi)(r)(L)
    Applying the above equations, I got E=(Q/[itex]\epsilon0[/itex])(1/((2pi)(r)(L))
    I then integrated as a function of r, and got V=(Q/[itex]\epsilon0[/itex])(1/((2pi)(L))(ln(r2/r1))
    I'm not too sure where to go from here, so any help would be greatly appreciated.
     
  2. jcsd
  3. Apr 21, 2012 #2

    rude man

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    Solve for Q.
    Then think Gauss.
     
    Last edited: Apr 21, 2012
  4. Apr 21, 2012 #3
    I solved for Q and got Q=(3.29[itex]\ast[/itex]10^8)/L
    then should I plug Q back in for the Q in the equation E=(Q/ϵ0)(1/((2pi)(r)(L))
     
  5. Apr 21, 2012 #4

    rude man

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    Yes, with of course the appropriate vaue for r.

    BTW I'm not checking your math, just your reasoning. Hope you understand the steps you took well.
     
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