Example 1. Parallel-plate capacitor(see Fig 4-2) Each of the two plates has an area a and the spacing bwtn them is s One carries a charge @, the other carries-Q So the field btwn is E=F=Eoa and the potential difference is V=Es the capacitance is 02 Say, A=(50 M)2, s=0.1mM, then C X 10+ F. It's greater than that of the earth