Final answer:
The flux of the electric field Φe through the two flat ends of the cylindrical Gaussian surface is 2EA, where EA is the flux through each end. The charge enclosed by the cylinder is σA. From Gauss's law, 2EA = σA.
Step-by-step explanation:
The flux of the electric field Φe through the two flat ends of the cylindrical Gaussian surface is given by 2EA, where EA is the flux through each end. Since there is no flux through the side of the cylinder, the total flux through the cylindrical surface is also 2EA. The charge enclosed by the cylinder is σA, where σ is the charge density and A is the area of the flat end. Therefore, from Gauss's law, 2EA = σA.