Question

Why is the flux through the flat ends of the coaxial cylinder zero for an infinite line charge?

Options

• Because the cylinder encloses no charge

• Because \[\vec E \perp d\vec A\] at the ends

• Because the electric field is zero everywhere on the cylinder

• Because \[\vec E \parallel d\vec A\] at the ends

Answer 1

At the flat ends, the electric field is perpendicular to the area vector. Therefore, the field has no component through those ends and their flux is zero.