Permittivity

• dielectric (or dielectric material or dielectric medium)
• $ϵ$ is the permittivity (or absolute permittivity) (מקדם דיאלקטרי) of a dielectric material
  • $\mathbf{D}=ϵ\mathbf{E}$
  • ${ϵ}_0=8.85\times 10^{-12}{\mathsf{C}}^2/N\cdot {\mathsf{m}}^2$ is the permittivity of free space (or vacuum permittivity or electric constant)
• The relative permittivity (or dielectric constant) of a dielectric material is defined as ${ϵ}_r=\frac{ϵ}{{ϵ}_0}$ (dimensionless)
  • ${ϵ}_r=\frac{C}{C_0}=\frac{E_0}{E}=\frac{V_0}{V}$
  • (sometimes denoted by $K$ or $\kappa$)
  • $C_0$, $E_0$, and $V_0$ are the capacitance, electric field, and voltage when the space between the plates of a capacitor is vacuum. $C$, $E$, and $V$ are the capacitance, electric field, and voltage when the space between the plates of a capacitor is filled with a dielectric material