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 September 2005
Email Alerts
Register now to receive SearchCIO-MidMarket.com-related news, tips and more, delivered to your inbox.
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States.
Privacy
More News and Tutorials
-
Backing up to local disk or tape can protect against the accidental destruction of a file but will do nothing to protect you when your facility suffers fire or flooding. Remote backup provides a better solution. This tip looks at two possibilities for remote backup: Choosing an outsourced remote backup service, or using software to do your own backups to an offsite facility.
-
Learn how attackers are using the widespread deployment of low-cost VoIP to leverage phishing attacks.
-
Is the government listening to your VoIP traffic? Can other companies spy on your WAN? It may sound like a paranoid conspiracy theory, but it's not that far out, technologically speaking. In this tip, Tom Lancaster looks at just how exposed your WAN traffic may be.
