4. The figure below shows the cross section of two long coaxial hollow metal cylinders. The inner cylinder with inner radius 4cm and outer radius 7cm has a uniform current Io. The outer cylinder with inner radius 10cm and outer radius 12cm has a current density J = (1/4πr) A/cm² where r is measured from the center of the cylinder. If the both currents flow in the same direction, into the page, what is the magnetic field at r = 11cm? Assume the magnetic permittivity inside the conductor and in free space is the same (Attention: Be sure to mark the correct answer. If you mark a wrong answer you will lose a) b) c) 2Holo 11π e) Ho 44π ) Зmolo 22π " 3μolo 44π CCW > CW d) Holo, CCW 11π ) CW CW 4cm 7cm 10m 12cm

4. The figure below shows the cross section of two long coaxial hollow metal cylinders. The inner cylinder with inner radius 4cm and outer radius 7cm has a uniform current Io. The outer cylinder with inner radius 10cm and outer radius 12cm has a current density J = (1/4πr) A/cm² where r is measured from the center of the cylinder. If the both currents flow in the same direction, into the page, what is the magnetic field at r = 11cm? Assume the magnetic permittivity inside the conductor and in free space is the same (Attention: Be sure to mark the correct answer. If you mark a wrong answer you will lose a) b) c) 2Holo 11π e) Ho 44π ) Зmolo 22π " 3μolo 44π CCW > CW d) Holo, CCW 11π ) CW CW 4cm 7cm 10m 12cm