Use the Biot-Savart Law to calculate the magnetic field B at point C, the common center of the semicircular arcs AD and HJ of radii R2 and R1 respectively, forming part of the circuit ADJHA that carries current I = 2 A as shown in the picture. Given that R2 = 2R1 = 20 cm, what will be the force exerted on a proton sitting at point C?