Outside the conductor: B is azimuthal, according to the circuital law 27B=10l.→B=A0 丌p Inside the conductor EpB=40J(p2),>B-koJpuolp 2丌7 20r×10 0 02030405060 p(millimeters) Figure 9-4 The magnetic induction B as a function of radius for a wire of I millimeter radius carrying a current of 1 ampere