2. A very long coaxial cylindrical cable is composed of an inner solid cylinder of radios R, and an outer hollow cylinder of radius R, .{The space between inner and outer cylinders is empty}. An electrical current I runs through the inner cylindrical wire and returns through the outer cylindrical wire.(a) Write down the magnetic energy density function for both inner and outer regions of the cable.(b) What is the energy per unit length L, for all regions (Both for inner and outer regions).

2. A very long coaxial cylindrical cable is composed of an inner solid cylinder of radios R, and an outer hollow cylinder of radius R, .{The space between inner and outer cylinders is empty}. An electrical current I runs through the inner cylindrical wire and returns through the outer cylindrical wire.(a) Write down the magnetic energy density function for both inner and outer regions of the cable.(b) What is the energy per unit length L, for all regions (Both for inner and outer regions).