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Electrical Engineering QUESTION #2165
Question 1
For a uniform plane wave in free space with $|\vec{E}| = 100\,\text{V/m}$, the average Poynting power density is:
  • $13.3\,\text{W/m}^2$✔️
  • $26.5\,\text{W/m}^2$
  • $53\,\text{W/m}^2$
  • $100\,\text{W/m}^2$
Correct Answer Explanation
$S_{avg} = \frac{|E|^2}{2\eta_0} = \frac{(100)^2}{2 \times 377} = \frac{10000}{754} \approx 13.3\,\text{W/m}^2$, where $\eta_0 = 377\,\Omega$.