The electric field has been measured to be horizontal and to the right everywhere on the closed box shown in the figure.

The electric field has been measured to be horizontal and to the right everywhere on the closed box shown in the figure. All over the left side of the box E1 = 120 V/m, and all over the right, slanting, side of the box E2 = 250 V/m. On the top the average field is E3 = 200 V/m, on the front and back the average field is E4 = 175 V/m, and on the bottom the average field is E5 = 220 V/m.