An infinitely long and straight wire carries a steady current I in the +z-direction at a distance d from the surface of a perfect conductor that occupies the half-space x > 0.
(a) Find the current density induced on the surface of the conductor.
(b) Remove the perfect conductor. Explain how one should locate a collection of N infinitely long and straight wires, and choose the current flowing in each wire, to effectively shield the vacuum spacex > 0 from the effect of the magnetic field produced by the current-carrying wire at x = −d.