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Homework Help: Current density and vector potential

  1. Sep 20, 2010 #1
    1. The problem statement, all variables and given/known data

    What current density would produce the vector potential
    A(r)=(-kmu/2pi)In(r/a) (in the z direction)

    where k is a constant, in cylindrical coordinates?

    2. Relevant equations

    3. The attempt at a solution

    i have done this three times and i get zero current density.So i am wondering if i am making a mistake, there is only one component for A the z component so when i use B=grad*A, i get a field in the fita direction, then when i use J=(grad*B)/mu i get zero.
  2. jcsd
  3. Sep 20, 2010 #2


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    Homework Helper
    Gold Member

    Hint: [itex]\frac{r}{r}[/itex] is undefined at [itex]r=0[/itex]:wink:
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