Question: It is found experimentally that the electric field in a certain region of Earth's atmosphere is directed vertically down. At an altitude of 310 m the field has magnitude 60.0 N/C. At an altitude of 220 m, the magnitude is 100 N/C.
Part A: Find the net amount of charge contained in a cube 90 m on edge, with horizontal faces at altitudes of 220 and 310 m. Neglect the curvature of Earth.
I don't just need an answer, work and explanations/walkthrough would be much appreciated! Thanks.