The magnetic field at the centre of a wire loop formed by two semicircular wires of radii $$R_1 = 2\pi$$ m and $$R_2 = 4\pi$$ m carrying current $$I = 4$$ A as per figure given below is $$\alpha \times 10^{-7}$$ T. The value of $$\alpha$$ is _____.
(Centre O is common for all segments)