Gauss’ Law for Electric Fields: relates electric flux density $D$ and electric charge density $\rho _v$
$$ \nabla \cdot \mathbf{D} = \rho_v \newline \oint_S \mathbf{D} \cdot d\mathbf{s} = Q_{enc}
$$
Gauss’ Law for Magnetic Fields: no magnetic monopoles, so magnetic flux density $B$ has no divergence
$$ \nabla \cdot \mathbf{B} = 0 \newline \oint_S \mathbf{B} \cdot d\mathbf{s} = 0
$$
Faraday’s Law of Induction: relates a time-varying magnetic field to an induced electric field
$$ \nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t} \newline \oint_C \mathbf{E} \cdot d\mathbf{l} = -\int_S \frac{\partial \mathbf{B}}{\partial t} \cdot d\mathbf{s}
$$
Ampere’s Law: relates magnetic fields to currents and time-varying electric fields