Question

Find the magnetic field generated by a wire along the line y=0.3 m at a point on the z axis at (0,0,0.4) m from the origin. Express your answer in component form!

Answer 1

B = mu I / 2 pi r, where mu I is the current

B will circle the wire and at the z axis it will be in the + or - x direction, depending on the direction of the current, unstated.

Answer 2

So find B from the distance to the wire of point (0,0, 0.4) and figure out the components. It will not have a component in z direction, for example.