Define electric flux density and relative permitivity as used in electrostatics?

Electric flux density, also known as electric displacement field, is a vector quantity that represents the electric flux passing through a unit area perpendicular to the direction of the electric field. It is denoted by D and is related to the electric field intensity E by the equation D = εE, where ε is the permittivity of the medium.

Relative permittivity, also known as dielectric constant, is a measure of how much a material can store electrical energy in an electric field. It is defined as the ratio of the permittivity of the material to the permittivity of free space (ε0). It is denoted by εr and is used to characterize the ability of a material to polarize in response to an applied electric field.