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Question:

The mean intensity of radiation on the surface of the Sun is about 108 W/m2. The rms value of the corresponding magnetic field is closest to:

10⁻⁶T

10⁻⁸T

10²T

1T

Solution:

The correct option is B 10⁻⁸T
I=ε₀cE²rms
Erms=cBrms
I=ε₀c³B²rms