Question

Application f Gauss's law

Answer 1

Gauss’s law is useful incalculating the electric field in problems, in which it is possible to choose a closed surface such that the electric field has a normal component which is either zero or has a single fixed (constant) value at every point on the surface. Such a closed surface, for a given charge distribution, is referred to as the ‘Gaussian Surface’ for that charge distribution. We can normally find such a Gaussian surface only for charge distributions that have a high degree of symmetry associated with them. It is only when we are able to think of a suitable Gaussian surface (for a given charge distribution) that we are able to use Gauss’s theorem for a simple calculation of electric fields.

Answer 2

However Coulomb's law can also be derived from Gauss's law. This is done by using this law to obtain the expression for the electric field due to a point charge. ... Hence, if we select, as a Gaussian surface, a spherical surface of radius r, at all points on this surface and the field is radial.