JEE Main 12 Jan 2019 Evening Question 18

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

[JEE Main Online Paper Held On 12-Jan-2019 Evening]

Options:

A) $ {10^{-2}}T $

B) $ 1T $

C) $ {10^{-4}}T $

D) $ 10^{2}T $

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Answer:

Correct Answer: C

Solution:

  • Mean intensity $ =\frac{B_rms^{2}}{{\mu_0}}c $
    $ \Rightarrow $ $ B_rms^{2}=\frac{10^{8}\times 4\pi \times {10^{-7}}}{3\times 10^{8}} $ $ B_rms^{{}}\approx {10^{-4}}T $