# How the value of permitivity of free space is determined?

when electric charges are placed on the medium then force of interaction between them decreases. We say this factor permitivity of the medium. The force of interaction between the charges is max if the charges are at space or if there is absence of medium. We know the electric permittivity of free space is $8.85 * 10^{-12} F/m$. My question is how this value is determined. Is there any experiment held?

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These days it has a defined value. WP describes the history. en.wikipedia.org/wiki/Permittivity_of_free_space#Value –  Ben Crowell May 23 '13 at 14:57
–  Ben Crowell May 23 '13 at 15:48