4. A long coaxial cable, crossection of which is shown in the figure, is made up of a cylindrical inner wire of radius a and a cylindrical shell shaped coaxial outer wire of inner radius b and outer radius c. The current density with magnitude /= x is spread over the cross section of the inner wire where the current has out-of-page direction. Outer wire carries uniformly distributed current i = Aka having into-the-page direction. a) Find the total current of the inner wire in in terms of i. Find expressions for the magnitude of magnetic field, b) inside the inner wire (r < a) c) between the wires (a c) in terms of Hg, i, n and r. For each case indicate the direction of the magnetic field as well.

4. A long coaxial cable, crossection of which is shown in the figure, is made up of a cylindrical inner wire of radius a and a cylindrical shell shaped coaxial outer wire of inner radius b and outer radius c. The current density with magnitude /= x is spread over the cross section of the inner wire where the current has out-of-page direction. Outer wire carries uniformly distributed current i = Aka having into-the-page direction. a) Find the total current of the inner wire in in terms of i. Find expressions for the magnitude of magnetic field, b) inside the inner wire (r < a) c) between the wires (a c) in terms of Hg, i, n and r. For each case indicate the direction of the magnetic field as well.