A long hollow cylindrical conductor has inner radius a and outer radius b and carries total current I uniformly through its conducting cross-section. Find B at a<r<b.
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A long hollow cylindrical conductor has inner radius a and outer radius b and carries total current I uniformly through its conducting cross-section. Find B at a<r<b.

G1 Physics · Accepted Answer

The enclosed fraction of current is (r²−a²)/(b²−a²). Applying Ampere's law gives the stated expression.