English: Diagram of electric fields in Faraday's ice pail experiment. A charged object (small sphere) is placed inside a conductive metal shell (large sphere). The electrostatic field of the interior charge causes the mobile charges in the metal to separate, inducing a positive charge on the inner surface of the shell, and a negative charge on the outer surface. It is found experimentally that the induced charge on the shell is exactly the same magnitude as the charge on the object. This can be proved by applying Gauss' Law to the Gaussian surface S contained inside the metal of the shell. Since S is inside the volume of metal, it is in a region of zero electric field. So the electric field flux through S is zero. Therefore the net charge inside S must be zero: