AP EAMCET · PHYSICS · Electromagnetic Waves
If the rms value of the electric field of electromagnetic waves at a distance of 3 m from a point source is \(3 \mathrm{~N} \mathrm{C}^{-1}\), then the power of the source is
- A 10.8 W
- B 8.1 W
- C 5.4 W
- D 2.7 W
Answer & Solution
Correct Answer
(D) 2.7 W
Step-by-step Solution
Detailed explanation
\(P = 4\pi \epsilon_0 c E_{rms}^2 r^2\) \(P = 4\pi (8.85 \times 10^{-12} \mathrm{~F/m}) (3 \times 10^8 \mathrm{~m/s}) (3 \mathrm{~N C^{-1}})^2 (3 \mathrm{~m})^2\) \(P = 2.7 \mathrm{~W}\)
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