Electromagnetic waves are radiated uniformly in all directions from a source. The rms electric field of the waves is measured 35 km from the source to have an rms value of 0.012 N/C. Determine the average total power radiated by the source. A)5.9 × 10³ W B)9.0 × 10³ W C)2.4 × 10⁴ W D)6.3 × 10⁴ W E)1.6 × 10⁵ W

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Quizplus · Accepted Answer

The average total power radiated by the source is given by:$$P_{avg}=\frac{1}{2}\epsilon_0cE_0^2(4\pi r^2)$$where:* $\epsilon_0$ is the permittivity of free space* $c$ is the speed of light* $E_0$ is the rms electric field* $r$ is the distance from the sourceSubstituting the given values into the equation, we get:$$P_{avg}=\frac{1}{2}(8.85	imes10^{-12}	ext{ C}^2/	ext{Nm}^2)(3	imes10^8	ext{ m/s})(0.012	ext{ N/C})^2(4\pi(35	imes10^3	ext{ m})^2)$$$$P_{avg}=5.9	imes10^3	ext{ W}$$Therefore, the correct choice is A.

Electromagnetic Waves Are Radiated Uniformly in All Directions from a Source