AIIMS 2019 Physics Electric Flux MCQ Question

To find the electric flux (Φ) through a surface in the Y⁻Z plane, we use the formula Φ = E · A, where E is the electric field vector and A is the area vector. The electric field given is E = (5î + 4ĵ + 9k̂), and since the surface lies in the Y⁻Z plane, the area vector A is oriented along the X-axis, specifically A = 20î (as the area is 20 units). Thus, the flux is calculated as Φ = E · A = (5î + 4ĵ + 9k̂) · (20î) = 100 units.

Options B (80 units), C (180 units), and D (20 units) are incorrect because they do not account for the correct orientation of the area vector or the magnitude of the electric field component in the direction of the area.