Question

For a Gaussian surface to be convenient for calculations, the electric field should be:

Options

• Random and changing at every point

• Always perpendicular to the enclosed charges

• Uniform and parallel to dS, or perpendicular to dS, at all points

• Always parallel to the surface

Answer 1

An ideal Gaussian surface is chosen such that the electric field E is either uniform and parallel to the area vector dS (making the dot product simple), or perpendicular to dS (making the dot product zero). This simplifies the calculation of electric flux significantly.