55. (a) From µ = iA = iπR 2 e we get i = µ πR 2 e = 8 .0 × 10 22 J / T π (6 . 37 × 10 6 m) 2 =6 . 3 × 10 8 A . (b) Yes, because far away from the Earth the ±elds of both the Earth itself and the current loop are dipole ±elds. If these two dipoles cancel each other out, then the net ±eld will be zero.
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.