Q 12-01-111JEE MainJEE Main 2021 (24 Feb, Shift 2)Medium
A point charge of $+12\ \mu\text{C}$ is at a distance 6 cm vertically above the centre of a square of side 12 cm as shown in figure. The magnitude of the electric flux through the square will be ______ $\times10^3\ \text{N m}^2\text{ C}^{-1}$.
Numerical value type. Enter your answer.
Answer: 226
The square is one face of a cube of side 12 cm with the charge at its centre (the centre is 6 cm from each face). By symmetry each face gets one sixth of the total flux:
$$\phi = \frac{q}{6\varepsilon_0} = \frac{12\times10^{-6}}{6\times8.85\times10^{-12}} \approx 2.26\times10^5 = 226\times10^3\ \text{N m}^2\text{ C}^{-1}$$
Solution by Sreeraj P, M.Sc Physics