Two Current Loops Are Coaxial and Coplanar

question 97

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) .