A Coaxial Cable Consists of an Inner Cylindrical Conductor of Radius

Essay

A coaxial cable consists of an inner cylindrical conductor of radius R₁ = 0.040 m on the axis of an outer hollow cylindrical conductor of inner radius R₂ = 0.080 m and outer radius R₃ = 0.090 m. The inner conductor carries current I₁ = 4.40 A in one direction, and the outer conductor carries current I₂ = 7.70 A in the opposite direction. What is the magnitude of the magnetic field at the following distances from the central axis of the cable? (μ₀ = 4π × 10^-7 T ∙ m/A)
(a) At r = 0.060 m (in the gap midway between the two conductors)
(b) At r = 0.150 m (outside the cable)