La loi de Gauss

Gauss's law states that the net electric flux through any closed surface is equal to the net charge enclosed by the surface divided by the permittivity of free space.

The closed surface which is a three-dimensional mathematical construct that can be any imaginary shape is called the Gaussian surface.

However, irrespective of the shape or size of the Gaussian surface, the total flux through it always depends only on the charge enclosed by it.

When there is a charge distribution, the total electric field can be determined using the principle of superposition. The net flux through the Gaussian surface by applying Gauss's law for individual charges equals the sum of only the charges enclosed by it.

Consider a point charge in a sphere. From Gauss's law, the electric field due to the enclosed charge can be obtained.

Using the expression for the force on a point charge due to an electric field, Gauss's law can be shown to be equivalent to Coulomb's law.