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Homework Help: EMM question

  1. Sep 8, 2009 #1
    urgent EMM question

    1. The problem statement, all variables and given/known data
    find the vector potential a distance s from an infinite straight wire carrying current I, check that dell dot A=0 and dellxA=B...

    ok i know the answer is A=A(s) z, in cylindricals. A(s)=(mu*I/2*pi)ln(s/a)z when a is a constant.

    can someone please explain to me why A points in the same direction as I????

    please, i need this asap, because i have no idea.
    Last edited: Sep 8, 2009
  2. jcsd
  3. Sep 9, 2009 #2


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    Re: urgent EMM question

    [tex]\vec{A}=\frac{\mu_{0}}{4\pi}\int_{V}\frac{\vec{J}}{|\vec{r}-\vec{r}\:'|}d^{3}r' [/tex]

    For an infinite straight wire, the direction of the current density J is fixed. Therefore ...
  4. Sep 9, 2009 #3
    Re: urgent EMM question

    Thankyou! = )
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