1 Why do we choose a spherical surface as gaussian surface for a point charge to calculate electric field? In my view, the reason may be i. If we take the point charge at centre, each point of spherical surface will be at same distance from the point charge and thus is equivalent.Thus electric field (perpendicular to the surface ) at every point of the surface will be equivalent . If we take other surface like cube , the distance between the point charge and every point of cube will be different.Then the calculation becomes hard. 2 Why do we choose a cylinderical surface for a infitely long char?ged sheet , why not other closed surface e.g. cube?