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Calculate the B field inside and outside a wire

  1. Sep 23, 2013 #1
    1. The problem statement, all variables and given/known data
    A long, straight wire of radius a has current density J = J0e−β(α−ρ)uz where β is a
    constant and ρ < α. Determine B inside and outside the wire.


    2. Relevant equations
    J=I/((pi)a^2)
    B=(μIρ)/(2(pi)(a)^2)

    3. The attempt at a solution
    Here is what I did B=(μρ/2)J0e^(-β(alpha-ρ))
     
    Last edited: Sep 23, 2013
  2. jcsd
  3. Sep 26, 2013 #2
    Is the problem confusing?
     
  4. Sep 26, 2013 #3
    Not at all. First find i by integrating J then find B. di = JdA
     
  5. Sep 26, 2013 #4
    So ∫J0e^-β(α-ρ) from 0 to a but what should I integrate with respect too?
     
  6. Sep 26, 2013 #5
    J=di/dA maybe?
     
  7. Sep 26, 2013 #6
    well since beta is constant and alpha is greater than rho then e^(-beta(alpha-rho)) whould go to 0 if I took the limit from 0 to infinty
     
  8. Sep 26, 2013 #7
    hmmm well I guess the problem does not consider time as it uses J0 which I assume stands for the intial value
     
  9. Sep 26, 2013 #8
    So my limit I idea is flawed then
     
  10. Sep 27, 2013 #9
    Anything else?
     
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