Two parallel, infinitely long, z- axis oriented conducting cylinders of radius "a" are a distance "b" apart. They are directly alongside the z axis and equidistant from it in the y-z plane. The cylinder center to center distance "b" is much, much, greater than "a". Both cylinders carry a current, "I", of the same magnitude but opposite direction. The current is flowing uniformly through the cross-section of the conductors. The cylinders are in a vacuum. Find the approximate H field at x = 10^6 "b