Why is electric flux zero on a cylinder aligned with the field?

[SAUMYA B]

The defination of electric flux on wiki is "is the rate of flow per unit area of the electric field. Electric flux is proportional to the number of electric field lines going through a virtual surface".

If we have a cylinder in an electric field placed along its length the net electric flux is zero.
As electric field lines pass through the cylinder , why is it then zero?

 

[jtbell]

The number of field lines that enter the cylinder, equals the number of field lines that leave the cylinder. The lines that enter, count as negative; the lines that leave, count as positive. Therfore the total is zero.