Q 12-08-162JEE MainJEE Main 2021 (22 Jul, Shift 1)Medium
Intensity of sunlight is observed as $0.092\ \text{W m}^{-2}$ at a point in free space. What will be the peak value of magnetic field at that point? ($\varepsilon_0 = 8.85\times10^{-12}\ \text{C}^2\text{ N}^{-1}\text{ m}^{-2}$)
Answer: (A) $2.77\times10^{-8}$ T
$I = \frac12c\varepsilon_0E_0^2 \Rightarrow E_0 = \sqrt{\dfrac{2\times0.092}{3\times10^8\times8.85\times10^{-12}}} \approx 8.33\ \text{V m}^{-1}$
$$B_0 = \frac{E_0}{c} \approx \frac{8.33}{3\times10^8} \approx 2.77\times10^{-8}\ \text{T}$$
Solution by Sreeraj P, M.Sc Physics