Ques. 1AIPMT 2006
A square surface of side L metres is in the plane of the paper. A uniform electric field E (volt/m), also in the plane of the paper is limited only to the lower half of the square surface (see figure). The electric flux in SI units associated with the surface is [figure]
- EL2
- EL2/2 0
- EL2/2
- zero
Answer
(4) zero
Solution
As per NCERT, electric flux through a surface: = E S = E S
The area vector of the square is normal to the plane of the paper, while E lies in the plane of the paper.
= 90 , 90 = 0
= 0 (no field line crosses the surface; this holds whatever part of the square the field covers).
Answer: (4)