Net electric flux through a closed surface with enclosed charge q is the integral of the dot product between the electric field and the instantaneous surface area vector.
The integral of the instantaneous surface area is simply the surface area vector.
The electric field at a distance outside a Gaussian surface will be constant at that specific distance.



Choose one that best fits its dimensions.
A solid sphere or spherical shell of charge Q would require the use of a sphere, while a line or rod of charge would require a cylinder.
A solid sphere or hollow spherical shell with uniform charge distribution can be treated as if all charge were concentrated at the center (a point charge), therefore the radius of your Gaussian surface would be the radius of your sphere plus the distance away from the sphere's surface.



Frequent formulas are 4pi r squared and pi r squared.
,


With the proper Gaussian surface, the electric field and surface area vectors will nearly always be parallel.

Know the formula for the electric flux through a closed surface.
Draw an imaginary Gaussian surface around your charge.
Determine the surface area of your Gaussian surface.Determine the electric field going through your Gaussian surface.
Multiply the magnitude of your surface area vector by the magnitude of your electric field vector and the cosine of the angle between them.Do not forget to add the proper units for electric flux.
{"src": "wikihow-all_validation", "title": "How to Calculate Electric Flux2"}