Conclusion: When a magnetic medium is brought into a magnetic field B (The matter will be magnetized; B (2) The magnetic field will matter also be influenced and changed: B=Bo+ B B' is the additional field(磁化附加场) due to the magnetization of matter and bo is the external field (pla 场)。Conclusion: When a magnetic medium is brought into a magnetic field (1)The matter will be magnetized; (2) The magnetic field will also be influenced and changed: B = B + B     is the additional field ( 磁 化 附 加 场 )due to the magnetization of matter and is the external field(外磁 场)。 B  B0  B0  matter B  