5. Coaxial cable (6 points) A long, straight coaxial cable consists of a thin conducting wire surrounded by a concentric cylindrical conductor of radius R = 0.02 m. The space in between is lled with insulation. The gure below shows a cross section. The inner wire carries a current [in : 1.7A in the z direction (out of the page), and the outer conductor carries an unknown current It,\"t . Outside the .._; cable the magnetic eld vanishes: B = 0. Example Final Exam 4 of 4 (a) (3 points) Use Ampre's law to nd the current [om carried by the outer conductor. Be sure to give the direction of the current. (b) (3 points) What is the magnetic eld at the point P, half way between the inner and outer conductor, at a radius R [2? Give both the magnitude and direction