This becomes really a very conceptual doubt . I have attached the figure below which explains my question best. The dimension of the finite square sheet (yes , it's a square) is l. The Gaussian surface taken in finite sheet case is a Cuboidal box grazing the sides of the sheet and extending to a height h (i.e dimensions of the Cuboidal Gaussian surface are l,l,h)
My questions are 1)Why has E been taken out of the Integral in the infinite sheet case ? 2) Is the Gaussian surface taken in the finite sheet case correct ? 3)Why will the Flux due to finite charged sheet not be pa^2/(2epsilon) (p is the charge density ? 4)Where is the difference in Flux through finite and infinite sheets coming from? 5) Finally what would be the E due to finite sheet at height h?