In general the electric displacement is given as $\mathbf{D}(\mathbf{r},t)=\varepsilon_0\mathbf{E}(\mathbf{r},t) + \mathbf{P}(\mathbf{r},t)$ where $\mathbf{P}$ accounts for the [polarization density](Polarization%20density.md) in a given medium, $\mathbf{E}(\mathbf{r},t)$ is the [electric field](Electric%20field.md), and $\varepsilon_0$ is the [vacuum permitivity](Vacuum%20permitivity.md). # In a vacuum Given an [electric field](Electric%20field.md) field source in a vacuum, the electric displacement and the Electric field differ only by [$\varepsilon_0$](Vacuum%20permitivity.md) acting as a multiplicative constant and thus $\mathbf{D}(\mathbf{r},t)=\varepsilon_0\mathbf{E}(\mathbf{r},t).$ #Electromagnetism