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logearav
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Homework Statement
In the case of calculating electric field due to an infinitely long line charge, we assume cylinder to be a gaussian surface and electric field and small area element of the cylinder acts along the same direction at the curved surface and they act perpendicular direction at the plane faces.
in the case of electric field due to an infinite plane sheet of charge we again assume cylinder to be a Gaussian surface but in this case at the plane faces electric field and surface element dA acts along the same direction and they act perpendicular along the curved surface. i am confused. please let me know how to visualise area element dA. i know electric field vector acts perpendicular to the surface but how to know the direction of the area element dA? help in this regard is greatly appreciated