Answer
The average power of the source is $4.88\times 10^4~W$
Work Step by Step
We can use $E_{rms}$ to find the intensity:
$I = c~\epsilon_0~E_{rms}^2$
$I = (3.0\times 10^8~m/s)~(8.85\times 10^{-12}~C^2/N~m^2)~(55\times 10^{-3}~V/m)^2$
$I = 8.0314\times 10^{-6}~W/m^2$
We can find the power of the source:
$I = \frac{P}{A}$
$P = I~A$
$P = I~(4\pi~r^2)$
$P = (8.0314\times 10^{-6}~W/m^2)(4\pi)~(22,000~m)^2$
$P = 4.88\times 10^4~W$
The average power of the source is $4.88\times 10^4~W$.
