Urgent: Understanding Vector Potential from a Straight Wire

[fredrick08]

urgent EMM question

Homework Statement

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.

 

[kuruman]

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

For an infinite straight wire, the direction of the current density J is fixed. Therefore ...

 

[fredrick08]

Thankyou! = )