मुक्त आकाश (free space) की परावैधुतता (permittivity) होती है

Surface density of charge on a sphere of radius R in terms of electric intensity E at a distance in free space is (epsi_(0) = permittivity of free space)

The product of permeability of free space and permittivity is -

The value of electric permittivity of free space is

What is the relation between the permittivity of free space e_(0) , the permeability of free space m_(0) and the speed of light in vaccum ?