In the figure, the two large, thin, non-conducting plates are parallel and close to each other. On their inner faces, the plates have excess surface charge densities of o1 = -4.00x10^-12 C/m^2 and o2 = +6.00x10^-12 C/m^2. (a) Find the electric field (magnitude and direction) in region I, in terms of 1/80.