Magnetic field of loop current
The above shows two loop currents with radii of \(r\) and \(2r,\) respectively, on the same plane. The current intensities are the same, which is \(I,\) and flow in opposite directions. What is the correct direction of the magnetic field at position \(O\) which is the center of the two loops?
Note: A(\(\odot\)) means magnetic field into the plane, and B(\(\otimes\)) means magnetic field out from the plane.