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Question: Answered & Verified by Expert
The rms value of the electric field of the light coming from the Sun is $720 \mathrm{~N} / \mathrm{C}$. The average total energy density of the electromagnetic wave is
PhysicsElectromagnetic WavesJEE MainJEE Main 2006
Options:
  • A
    $3.3 \times 10^{-3} \mathrm{~J} / \mathrm{m}^3$
  • B
    $4.58 \times 10^{-6} \mathrm{~J} / \mathrm{m}^3$
  • C
    $6.37 \times 10^{-9} \mathrm{~J} / \mathrm{m}^3$
  • D
    $81.35 \times 10^{-12} \mathrm{~J} / \mathrm{m}^3$
Solution:
1900 Upvotes Verified Answer
The correct answer is:
$4.58 \times 10^{-6} \mathrm{~J} / \mathrm{m}^3$
$U_{a v}=\varepsilon_0 E_{\text {rs }}^2=4.58 \times 10^{-6} \mathrm{~J} / \mathrm{m}^3$
$E_{\text {rms }}=4.58 \times 10^{-6} \mathrm{~J} / \mathrm{m}^3$

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