1. The problem statement, all variables and given/known data "A wire is formed into the shape of two half circles connected by equal-length straight sections. A current I flows in the circuit clockwise as shown. Determine (a) The magnitude and the direction of the magnetic field at the center, C, and (b) the magnetic dipole moment of the circuit" http://img225.imageshack.us/img225/4218/untitled1mm6.jpg [Broken] 2. Relevant equations Biot-Savart Law -> dB = (Mu * I * dL) / (4 * Pi * R^2) 3. The attempt at a solution The answer is ( Mu * I * [R1 + R2] )/ (4 * R1 * R2) Not sure how they get it, I'm seeing it as two half circles and you minus them from each other. B = ( Mu * I * [2 * Pi * R1 / 2] ) / (4 * Pi * R1^2) B1 = (Mu * I) / (2 * R1) B2 = (Mu * I) / (2 * R2) Bt = B1 + B2 ?