Q 12-08-217JEE MainJEE Main 2019 (12 Jan, Shift 2)Medium
The mean intensity of radiation on the surface of the Sun is about $10^{8}\ \text{W/m}^2$. The rms value of the corresponding magnetic field is closest to:
Answer: (D) $10^{-4}$ T
$I = \dfrac{cB_{\text{rms}}^2}{\mu_0}$, so
$$B_{\text{rms}} = \sqrt{\frac{\mu_0I}{c}} = \sqrt{\frac{4\pi\times10^{-7}\times10^8}{3\times10^8}} \approx 6.5\times10^{-4}\ \text{T}$$
which is of the order of $10^{-4}$ T.
Solution by Sreeraj P, M.Sc Physics