In fair weather, over flat ground, there may be a downward electric field of 185
ID: 2176001 • Letter: I
Question
In fair weather, over flat ground, there may be a downward electric field of 185 N/C.(a) Assume that the Earth is a conducting sphere with charge on its surface. If the electric field just outside is 185 N/C pointing radially inward, calculate the total charge on the Earth and the charge per unit area. (in C & nC/m^3 respectively)
(b) At an altitude of 260 m above the Earth's surface, the field is only 155 N/C. Calculate the charge density of the air (in C/m^2)...(assumed constant). [Hint: See the Conceptual Example within the chapter that discusses "Field Lines for a Thin Spherical Shell".]
Explanation / Answer
185 = 8.99e9*Q/(6.4e6*6.4e6) >>>>> Q = 842892 C Q/V = 842892e9/((4/3)*3.14*6.4e6*6.4e6*6.4e6) >>>> Q/V = 7.68 * 10^-7 nC/m3