Chapter 22, Problem 22.37P

The electric field ${\stackrel{\to }{E}}_1$ at one face of a parallelepiped is uniform over the entire face and is directed out of the face. At the opposite face, the electric field ${\stackrel{\to }{E}}_2$ is also uniform over the entire face and is directed into that face (Fig. P22.37). The two faces in question are inclined at 30.0° from the horizontal, while both ${\stackrel{\to }{E}}_1$ and ${\stackrel{\to }{E}}_2$ are horizontal; ${\stackrel{\to }{E}}_1$ has a magnitude of 2.50 × 10⁴ N/C, and ${\stackrel{\to }{E}}_2$ has a magnitude of 7.00 × 10⁴ N/C. (a) Assuming that no other electric field lines cross the surfaces of the parallelepiped, determine the net charge contained within, (b) Is the electric field produced by the charges only within the parallelepiped, or is the field also due to charges outside the parallelepiped? How can you tell?

Figure P22.37