A 10 cm x 10 cm flat plate is located 5 cm from a point charge of 10-8 C. What is the electric flux through the plate due to the point charge?
The easiest way to solve this problem is to consider the flat plate to be one side of a cube centered on the charge. Since the electric field of the charge is symmetrical, all six sides of the cube must have the same flux, which is 1/6 of the total flux.