In diamagnetic materials, the external magnetic field $$\boldsymbol{B}$$ is weakened by the magnetization $$\boldsymbol{M}$$ of the material, so that the internal magnetic field $$\boldsymbol{B}_{\text i}$$, i.e. the magnetic field within the material is smaller. The magnetic susceptibility $$\chi$$ is negative in the case of diamagnetism:$$\boldsymbol{B}_{\text i} = \boldsymbol{B} - \chi \, \boldsymbol{B}$$