Chapter-1|Electric Charges and Fields | NCERT 12th Physics:
Area Vector:
The vector associated with every area element of a closed surface is taken to be in the direction of the outward normal. Thus the area element vector ∆S at a point on a closed surface is equal to ∆Sn∧, where ∆S is magnitude of area element and n^ is a unit vector in the direction of outward normal at the point.
Note:- Area vector is always perpendicular to the surface.
