Here's is a quote from(adsbygoogle = window.adsbygoogle || []).push({}); Electromagneticsby Richard H. Selfridge, David V. Arnold, and Karl F. Warnick:

I am still not sure where that 1/2 factor comes from... The electric field energy density 3-form is

[tex]\omega_e = \frac{1}{2} E\wedge D [/tex]

where the factor of 1/2 arises from the way the electric field has been defined. (If two charges are near each other, stored potential energy can be converted to kinetic energy by allowing one charge to accelerate away. The energy of the field due to the second charge remains but cannot be extracted, so we exclude it from the definition of [itex]\omega_e[/itex])

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Energy Density 3-Form

**Physics Forums | Science Articles, Homework Help, Discussion**