This discussion clarifies the concept of electric flux through different geometric shapes, specifically a disk, cube, and sphere. The key conclusion is that the electric flux through a closed surface, such as a cube or sphere, is zero when no charges are enclosed within that surface. This is due to the principle that electric field lines entering one face of the closed surface must exit through another, resulting in no net flux. In contrast, the flux through an open surface like a disk can be non-zero, as it does not enclose a volume.
PREREQUISITESStudents of physics, particularly those studying electromagnetism, educators teaching electric flux concepts, and anyone seeking to deepen their understanding of electric fields and their interactions with different geometrical shapes.
You've got the right idea. The disc is an open surface whereas the cube and sphere are closed surfaces, this means that they enclose a volume. Now since there are no charges inside these surfaces, any electric field lines that pass through one of the faces of the cube, must also pass out of another face. The same is true of the sphere. Therefore, there is as much flux entering the cube and sphere as there is leaving it, hence the net flux through those surfaces is zero.faller217 said:I am studying electric flux through both a disk, cube, and sphere. I understand how the flux is calculated in a disk, but I don't understand how the flux through a cube with the point charge outside the cube is equal to zero when the disk is not. Is this because the disk is 2-D?
Thank you for your help