Q. A square surface of side L meter in the plane of the paper is placed in a uniform electric field E (volt/m) acting along the same plane at an angle θ with the horizontal side of the square. The electric flux linked to the surface, in units of volt-m, is
A) Zero
B) EL²
C) EL² cos θ
D) EL² sin θ
Explanation
[Solution from source] Flux = E·A cos(angle between E and the area vector). The area vector is normal to the paper, while E lies in the plane of the paper, so the angle is 90° and the flux is zero for any θ. EL² cos θ wrongly treats θ as the angle with the normal. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.