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The magnitude of the earth\'s magnetic field, B, at either geomagnetic pole, is

ID: 1611645 • Letter: T

Question

The magnitude of the earth's magnetic field, B, at either geomagnetic pole, is about 0.7 G = 7 x 10^-5 T. Using a model in which you assume that this field is produced by a single current loop around the equator, determine the current that would generate such a field. (Re = 6.37 x 10^6 m.)

I know I use u0*NiA/2*pi*z3 I'm struggling with how to find z. Is it just the radius of the Earth or will it be the distance along the surface from the north pole to the center of the equator (center of the current carrying loop)? Any help with this would be appreciated. Thanks

Explanation / Answer


magnetic field due to current carrying circular loop

B = uo*I/(2r)

r = RE = 6.37*10^6 m

I = current in the circular loop

B = 7*10^-5 T

7*10^-5 = 4*pi*10^-7*I/(2*6.37*10^6)

current I = 7.1*10^8 A