In a particular region of Earth's atmosphere, the electric field above Earth's surface has been measured to be 140 N/C downward at an altitude of 280...

In a particular region of Earth's atmosphere, the electric field above Earth's surface has been measured to be 140 N/C downward at an altitude of 280 m and 164 N/C downward at an altitude of 430 m. Calculate the volume charge density of the atmosphere, assuming it to be uniform between 280 and 430 m. (Hint: You may neglect the curvature of Earth. Why?)