4) Assume that w=1cm and d varies between 1lmm and 4cm . Plot the dependence of the capacitance C vs. the separation (take as many points as you feel are sufficient to represent the dependence properly). Every point in this dependence is obtained by solving the formulated integral equation for the (discretized) surface charges and then finding the capacitance. On the same figure, plot the capacitance of the parallel plate capacitor obtained via the approximate formula C = .Ec,aj / d. Comment on when this formula 1s closer to the results obtained via the numerical solution