this question has three parts. i figured out the first and second one. i just dont understand electrical potential energy. Consider the Earth and a cloud layer 820m above the Earth to be the plates of a parallel-plate capacitor. If the cloud layer has an area of 1.27 km2 = 1.27E+6 m2, what is the capacitance? 1.37×10-8 F If an electric field strength greater than 4.91E+6 N/C causes the air to break down and conduct charge (lightning), what is the maximum charge the cloud can hold? 55.15C If the cloud is holding this maximum charge, what is the magnitude of the difference in electric potential between the cloud and the ground? i took the V the i found in the second problem which was 4.026E9V. and i took q from the second problem and multiplied it by V. i ended up getting 2.22E11. which is wrong..what am i doing wrong? i think i might be using the wrong formulas.