QAIPMT-2006-Ph-2466: NEET 2006 Physics - Class 11 AIPMT-2006-Ph-2466 Solution: A square surface of side L metres is in the plane of the paper. …

**1. Definition of Electric Flux ($\Phi$):** The electric flux through a surface depends on the dot product of the electric field vector ($\vec{E}$) and the area vector ($\vec{A}$): Where $\theta$ is the angle between the electric field direction and the normal (perpendicular) to the surface. **2. Orientations of the Vectors:** - **Area Vector ($\vec{A}$):** Since the square surface lies flat **in the plane of the paper**, its area vector points perpendicular to the page (straight outwards or inwards). - **Electric Field Vector ($\vec{E}$):** The problem states that the electric field lines also lie entirely **in the plane of the paper**. **3. Evaluate the Angle ($\theta$):** Because the electric field lies flat on the page and the area vector points straight out of the page, they are perfectly perpendicular to each other: **4. Calculate the Flux:** Since $\cos(90^\circ) = 0$: