1. The problem statement, all variables and given/known data Consider a circular ring of wire of radius a that resides in the x-y plane through the origin. The center of the ring coincides with the origin and you can regard the thickness of the wire to be infinitesimal. a. Given that a current I flows in the ring, find an expression for the current density J. 2. Relevant equations ∫B(r).dl = μ∫J(r).da 3. The attempt at a solution ok, I know J(r)=Io * δ(x)*δ(y) z How do I get this in cylindrical coordinates (ρ,θ,z)?