Formula_20715

\[\begin{gathered}\operatorname{rot} \boldsymbol{e}_{k}=-\frac{\partial \boldsymbol{h}_{k}}{c \partial t}, \quad \operatorname{rot} \boldsymbol{h}_{k}=\frac{4 \pi J_{k}}{c}+\frac{\partial \boldsymbol{e}_{k}}{c \partial t}, \\\operatorname{div} \boldsymbol{e}_{k}=4 \pi \rho_{k}, \quad \operatorname{div} \boldsymbol{h}_{k}=0 .\end{gathered}\]