Understanding and Application of Gauss Theorem in Electrostatic Field

Correct understanding and mastering electrostatic field of Gauss theorem is the key part of learning electromagnetism, the field strength E in Gaussian theorem is the total field strength excited by all charges in the space on the closed surface, E=Ein+Eout. The sum of E refers to the algebra sum of charges in the closed surface, When charge distribution has certain symmetry(Spherical symmetry, axial symmetry, plane symmetry), we can use Gauss theorem to calculate the distribution of the electric field.