The rms value of the magnitude of the magnetic field in an electromagnetic wave

Question

The rms value of the magnitude of the magnetic field in an electromagnetic wave is 0.235 T. The speed of light is 3 × 10^8 m / s and permeability of free space is 4 × 10^ 7 T · m / A. Find the rms value is of the electric field. Answer in units of V / m.

Find average energy density. Answer in units of nJ / m^3 .

Find the intensity. Answer in units of W / m^2 .

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I just need the answer to the last two parts. The answer to the first part is 70.5 V/m

Explanation / Answer

Erms/Brms = c

Erms = 3 *10^8 * 0.235 *10^-6

Erms = 70.5 N/C ======part a)

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Average energy density = Erms^2/(c^2*u0)

Average energy density = 70.5^2/((3*10^8)^2 * u0) = 43.95 nJ/m^3 =====part b)

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intensity = Average energy density * c

intensity = 4.395 *10^-8 * 3 *10^8 = 13.2 W/m^2 =================part c)

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