At each point on the surface of the cube shown in Figure 23-27, the electric field is parallel to the z axis. The length of each edge of the cube is...

At each point on the surface of the cube shown in Figure 23-27, the electric field is parallel to the z axis. The length of each edge of the cube is 3.0 m. On the top face of the cube E = -40 k N/C, and on the bottom face of the cube E = +25 k N/C. Determine the net charge contained within the cube.