Two Current Loops Are Coaxial and Coplanar

question 89

Multiple Choice

Two current loops are coaxial and coplanar. One has radius a and the other has radius 2a. Current 2I in the outer loop is parallel to current I in the inner loop. The magnitude of the magnetic field at the center of the two loops is

• A) 0.
• B) .
• C) .
• D) .
• E) .