Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
In addition to the revision notes for Electric Flux. Gauss Law on this page, you can also access the following Electrostatics learning resources for Electric Flux. Gauss Law
| Tutorial ID | Title | Tutorial | Video Tutorial | Revision Notes | Revision Questions | |
|---|---|---|---|---|---|---|
| 14.6 | Electric Flux. Gauss Law |
In these revision notes for Electric Flux. Gauss Law, we cover the following key points:
In some cases, it is convenient to appoint a vector to a given area, in order to make it operable with other vector quantities. This trick is especially common in electromagnetism. Thus, instead of writing the surface area as A square units, we consider the corresponding area vector of A⃗ units which is perpendicular to the given surface.
If another vector quantity is multiplied by a given area vector, we consider the angle between them as a part of multiplication. The introduction of area vector creates the possibility to apply both the dot and cross product of the two vectors, as needed.
By definition, electric flux is the amount (number) of electric field lines (i.e. the electric field E) flowing through a closed loop of area A.
Mathematically, we have
Electric flux Φ is a scalar quantity because it is obtained through the dot product of two vectors, E and A. Hence, the formula of electric flux becomes
When electric field lines are perpendicular to the loop plane, the two vectors E and A are parallel, i.e. they form an angle of 0° or 180° to each other. Since cos 0° = 1 and cos 180° = -1, the electric flux takes its maximum or minimum values for these angles.
The unit of electric flux is
The electric flux Φ of a charged sphere is
Here we have made use of the equation of the area of a sphere A = 4πR2 and that of electric field of a point charge E = Q/4πϵ0R2.
The last formula is one of the many representations of the Gauss Law, which in simple word says:
The net outward normal electric flux through any closed surface is proportional to the total electric charge enclosed within that closed surface.
The sphere we considered above is called Gaussian Sphere. As you see, the electric flux does not depend on the radius of sphere but only on the amount of charge it carries at its centre.
The total electric flux flowing through a cube is
Enjoy the "Electric Flux. Gauss Law" revision notes? People who liked the "Electric Flux. Gauss Law" revision notes found the following resources useful:
Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
We hope you found this Physics tutorial "Electric Flux. Gauss Law" useful. If you did it would be great if you could spare the time to rate this physics tutorial (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.