Two current loops have their centres at $(0,0,0)*$ and $(0,0,4)$ their axes on the z axis. The first one located at the origin has a radius of m and carries a current of $2$ A in ap$,$ while the second one has a radius of $6$ m and carries a current of $4\mathrm{.}5$ A in ap$.$ Determine the magnetic field H at:

$($a$)(0,0,0)$

$($b$)(0,0,3)$

ibrica de eva