A circular loop of radius carries steady current . At what axial distance from the center of the loop is the magnetic field equal to of its value at the center?
Answer and explanation
Correct answer: D.
- Step 1: Center field is . Axial field is .
- Step 2: Equating: .
- Step 3: Taking cube roots: .
Answer
.
Why not the others: gives ; gives ; and gives .
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