Sähkökenttävakio

Sähkökenttävakio, often translated as permittivity of free space, is a fundamental physical constant denoted by the symbol $\epsilon_0$. It quantifies the capability of a vacuum to permit electric fields. In simpler terms, it describes how easily an electric field can be established in a vacuum.

The value of $\epsilon_0$ is approximately $8.854 \times 10^{-12}$ farads per meter (F/m). This constant appears in many equations in electromagnetism, most notably in Coulomb's Law, which describes the force between two electric charges. Coulomb's Law states that the force $F$ between two point charges $q_1$ and $q_2$ separated by a distance $r$ is given by $F = \frac{1}{4\pi\epsilon_0} \frac{q_1 q_2}{r^2}$.

The permittivity of free space is also related to the permeability of free space ($\mu_0$) and the speed of light in a vacuum ($c$) by the equation $c^2 = \frac{1}{\epsilon_0 \mu_0}$. This relationship highlights the deep connection between electricity, magnetism, and light.

In materials other than a vacuum, the permittivity is described by the relative permittivity (also known as the dielectric constant) multiplied by $\epsilon_0$. This relative permittivity indicates how much the electric field is reduced by the material compared to a vacuum. A vacuum has a relative permittivity of exactly 1 by definition.