A coaxial cable having radius "a" of inner wire and inner and outer radii"b"and"c"respectively of the outer shell carries equal and opposite currents of magnitude i on the inner and outer conductors as shown. What is the magnitude of the magnetic induction at point P of the cable at a distance r (b < r < c) from the axis?
(A) Zero
(B) μ0ir/2πa2
(C) μ0i/2πr
(D) μ0i/2πr c2 - r2 / c2 - b2
