A currentI flows in a semi-infinite straight wire along y= 2b, z = 0 from very large positive values of x to the point (0,2b,0), then around a semicircular wire centered upon (0,b,0) in negative values of x to the point (0,0,0), then along a second semi-infinite straight wire along y = 0, z = 0from the point (0,0,0) to very large positive values of x. Discover the magnetic field produced at the point(0,b,0)