The divergence of the field is equal to zero.

The curl of the field is equal to zero.

The curl of the field is equal to $$ - {{\partial \,B} \over {\partial \,t}}$$.

The Laplacian of the field is equal to $$\mu \,\,\varepsilon {{{\partial ^2}\,E} \over {\partial \,{t^2}}}$$.