A circular capacitor of radius r is made using SiO2 as the dielectric on a silicon wafer. If a trench of depth l is made to replace the circular capacitor with the trench capacitor with trench depth l, find the ratio of the two capacitances. (Assume the thickness of SiO2 is small enough to neglect its effect on the dimensions of the trench capacitor.) If the radius r = 2micromemters and the trench depth is 10micrometers, find the capacitance ratio.