Initial(solid line) and final (dotted lines except for 10 G in short dashed lines) mass fraction abundances of H and He vs. the optical depth for a B2 V star model with the diffusion processes and different magnetic field strengths (10, 200, 500, 1000, and 2000 G). Left panels: the Lorentz force is inward directed (F_L-in). Right panels: the Lorentz force is outward directed (F_L-out).