Infinite surfaces carrying surface currents with translational symmetry in one direction are considered. When the magnetic field is treated as a bivector quantity rather than an axial vector quantity, its simple relation to the plane visual angle of the surface becomes easy to establish by means of the Biot-Savart law. If the surface with the current divides the space into two parts, the magnetic field is uniform in these parts and has a value proportional to the visual angle. >