Another word for permittivity is "dielectric constant." Both terms refer to the same concept in electromagnetism and materials science.
Permittivity, symbolized by \(\epsilon\), is a measure of how much electric field (or electric flux) a material can "permit" or support within itself. It essentially quantifies the ability of a material to store electrical energy in an electric field.
The dielectric constant is a dimensionless quantity that describes how much a material can increase the capacitance of a capacitor compared to the capacitance in a vacuum. In essence, the dielectric constant is the ratio of the permittivity of the material to the permittivity of free space (\(\epsilon_0\)):
\[ \text{Dielectric Constant} = \frac{\epsilon}{\epsilon_0} \]
Where:
- \(\epsilon\) is the absolute permittivity of the material.
- \(\epsilon_0\) is the permittivity of free space (approximately \(8.854 \times 10^{-12} \, \text{F/m}\)).
So, while "permittivity" is the more general term that refers to the absolute measure, "dielectric constant" typically refers to the relative measure when comparing a material to vacuum.