Definition:Electric Flux Density

Definition
Electric flux density is the measure of the intensity of an electric field inside a substance $S$.

It is defined as:
 * $\mathbf D = \varepsilon_0 \varepsilon_r \mathbf E$

where:
 * $\mathbf E$ denotes the electric field strength at a given point within $S$
 * $\varepsilon_0$ denotes the vacuum permittivity
 * $\varepsilon_r$ denotes the relative permittivity of $S$

Electric flux density is a vector quantity.