Answer
See answers.
Work Step by Step
The intensity is the power per unit area. The 1800W of power is distributed uniformly over the surface area of the sphere.
$$\overline{I}=\frac{P}{A}=\frac{1800W}{4\pi (5.0m)^2}=5.7\frac{W}{m^2}$$
The energy per unit area per unit time is the magnitude of the average intensity, equation 22–8. Find the rms value of the electric field.
$$\overline{I}=\frac{1}{2}\epsilon_ocE_o^2=\frac{1}{2}\epsilon_oc(\sqrt{2}E_{rms})^2=\epsilon_ocE_{rms}^2$$
$$E_{rms}=\sqrt{\frac{\overline{I}}{\epsilon_oc }}$$
$$=\sqrt{\frac{5.730W/m^2}{(8.85\times10^{-12} C^2/(N\cdot m^2))(3.00\times10^8m/s)}}=46V/m$$
