Chapter 23, Problem 6P

At each point on the surface of the cube shown in Fig. 23-31, 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 the field is $\stackrel{\to }{E}$ = -34 $\hat{k}$ N/C, and on the bottom face it is $\stackrel{\to }{E}$ = + 20 $\hat{k}$ N/C. Determine the net charge contained within the cube.