Can anyone explain how to go from:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]I_s = \frac{nc\epsilon}{2} |E|^2 [/tex]

to

[tex]I_s = \frac{nc}{8\pi} |E|^2 [/tex]

That means [tex] \epsilon [/tex] is [tex] \frac{1}{4\pi} [/tex]....I can't find that anywhere.

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# Homework Help: Intensity of Electric field

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