3. diamagnetic substance: P=0 Because of p=0 the external field cannot influence the molecules, but the lorentz force act on the electrons in the atom and their orbits will be in precession(tzf)about the direction of bo axis B 目■■ B B Gravity of Earth3. diamagnetic substance: Pm = 0  Because of , the external field cannot influence the molecules, but the Lorentz force act on the electrons in the atom and their orbits will be in precession(进动）about the direction of : Pm = 0  B0  axis Gravity of Earth B0  B0  B  B 