## Fundamentals of Physics Extended (10th Edition)

$I=0.0053W/m^2$
The average intensity of electromagnetic radiation is equal to the average value of the Poynting vector, which is equal to $$S=\frac{E_mB_m}{2\mu_o}$$ Using the fact that $B_m=\frac{E_m}{c}$, the formula becomes $$S=\frac{E_m^2}{2\mu_o c}$$ Substituting known values of $E_m=2.0V/m$, $\mu_o=4\pi \times 10^{-7} H/m$, and $c=3.00\times 10^8m/s$ yields an average intensity of $$S=\frac{(2.0V/m)^2}{2(4\pi \times 10^{-7}H/m)(3.00\times 10^8m/s)}=0.0053W/m^2$$