1. The problem statement, all variables and given/known data In a particular region of Earth's atmosphere, the electric field above Earth's surface has been measured to be 147 N/C downward at an altitude of 260 m and 165 N/C downward at an altitude of 410 m. Calculate the volume charge density of the atmosphere, assuming it to be uniform between 260 and 410 m. (Hint: You may neglect the curvature of Earth. Why?) 2. Relevant equations volume charge density = Q/V I tried doing E=kq/r^2 for the 147 N/C and 260m altitude. -147=(9*10^9)(q)/(260)^2_ and got -0.0011 C. I divided that by volume (4/3*pi*260^3) which gave me -1.5e-11, but that wasn't right. I really have no idea how to even start this. Why did they give me 2 sets of altitude and E field?