permittivity of free space
The permittivity of free space (a vacuum) is a physical constant equal to approximately 8.85 x 10
-12 farad per
meter (F/m). It is symbolized
o. In general,
permittivity is symbolized
and is a constant of proportionality that exists between electric displacement and electric field intensity in a given medium. In many materials,
particularly glass and certain plastics,
is substantially greater than
o.
If o represents the permittivity of free space (that is, 8.85 x 10-12 F/m) and s represents the permittivity of a particular substance (also specified in farads per meter), then the relative permittivity, also called the dielectric constant r, of that particular substance is given by:
r = s / o
= s x 1.13 x 1011
Also see Table of Physical Units and Constants.
This was last updated in July 2002
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