Walker, Halliday & Resnick — Gauss' Law: Problem 14

14 At each point on the surface of the cube shown in Fig. 23-29, the electric field is parallel to the z axis. The length of each edge of the cube is 4.0 m. On the top face of the cube the field is \(\vec{E} = -34\hat{k}\text{ N/C}\), and on the bottom face it is \(\vec{E} = +20\hat{k}\text{ N/C}\). Determine the net charge contained within the cube.