The earth can be considered as a single-conductor capacitor. It can also be considered in combination with a charged layer of the atmosphere, the ionosphere, as a spherical capacitor with two plates, the surface of the earth being the negative plate. The ionosphere is at a level of about 70 km, and the potential difference between earth and ionosphere is about 350000 V. A. Calculate the capacitance of this system. B. Find the total charge on this capacitor. C. Find the energy stored in this system.