Q 12-01-165JEE MainJEE Main 2025 (7 Apr, Shift 2)Easy
The electric field in a region is given by $\vec E = (2\hat i + 4\hat j + 6\hat k)\times10^3\ \text{N/C}$. The flux of the field through a rectangular surface parallel to the $x$–$z$ plane is $6.0\ \text{N m}^2\text{C}^{-1}$. The area of the surface is ______ $\text{cm}^2$.
Numerical value type. Enter your answer.
Answer: 15
A surface parallel to the $x$–$z$ plane has its area vector along $\hat j$, so only $E_y$ contributes:
$$\phi = E_yA \Rightarrow 6 = 4\times10^3A \Rightarrow A = 1.5\times10^{-3}\ \text{m}^2 = 15\ \text{cm}^2$$
Solution by Sreeraj P, M.Sc Physics