The reason Gauss's law does not apply to charges outside the area is because Gauss's law is based on the concept of symmetry. It assumes that the electric field lines are equally distributed in all directions around a charge. However, this is not always the case when considering charges outside the area.
In some cases, Gauss's law can be applied to charges outside the area. This is known as the "Gauss's law for enclosed charges" and involves calculating the electric field at a point outside the area by considering the charges enclosed within a surface surrounding that point.
If Gauss's law is applied to charges outside the area without considering the enclosed charges, it will not give an accurate result. This is because the electric field lines may not be symmetrical around the charge and the flux through the surface will not be equal to the enclosed charge.
There are some special cases where Gauss's law can be applied to charges outside the area. For example, if the charges outside the area are distributed in a symmetrical pattern, then Gauss's law can be used to calculate the electric field at a point outside the area.
To calculate the electric field at a point outside the area, we can use the principle of superposition. This involves taking into account the contributions of all the charges outside the area and the charges enclosed within a surface surrounding the point of interest. The resulting electric field will be the sum of the individual electric fields due to each charge.