Question

The mean intensity of radiation on the surface of the Sun is about ${10}^{8}W/m^2$. The rms value of the corresponding magnetic field is closest to:

• A. ${10}^{2}T$
• B. ${10}^{-4}T$
• C. $1T$
• D. ${10}^{-2}T$

Answer 1

Answer: (B)

${10}^{-4}T$

$I={\epsilon }_{0}C{E}_{rms}^2\&E_{rms}=c{B}_{rms}$
$I={\epsilon }_0{C}^3{B}_{rms}^2$
$B_{rms}=\sqrt{\frac{1}{{\in }_0{C}^3}}$
$B_{rms}\approx {10}^{-4}$