 Electric displacement field

The electric displacement is $\mathbf{D}={ϵ}_0\mathbf{E}+\mathbf{P}$ and obeys $\nabla \cdot \mathbf{D}={\rho }_{\mathrm{free}}$. In a linear isotropic dielectric, $\mathbf{D}=ϵ\mathbf{E}$.

The electric displacement field, often denoted by \( \mathbf{D} \), is a vector field that describes the effects of free and bound charge in a medium. It is particularly useful in the context of electromagnetism and dielectric materials, whereby it helps in dealing with polarization effects.