Two thin coils of radius 3 cm are 20 cm apart and concentric with a common axis,as shown in the figure below. Both coils contain 10 turns of wire with a conventional current of 2 amperes that runs counterclockwise as viewed from the right side. You may assume a coordinate system in which +x points to the right, +y points to the top of the page, and +z points out of the page.
(a) What is the vector magnetic field on the axis, halfway between the two loops?
(b) What is the vector magnetic field at the point on the axis halfway between the loops if the current in the right loop is reversed?
(c) What is the magnitude of the magnetic dipole moment of one of the coils of wire?