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8.Electromagnetic waves
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The intensity of light from a source is $\left( {\frac{{500}}{\pi }} \right)W/{m^2}$ . Find the amplitude of electric field in this wave
A
$\sqrt 3 \times {10^{2\,}}\,N/C$
B
$2\sqrt 3 \times {10^{2\,}}\,N/C$
C
$\frac{{\sqrt 3 }}{2} \times {10^{2\,}}\,N/C$
D
$2\sqrt 3 \times {10^{1\,}}\,N/C$
Solution
$I=\frac{I}{2} \epsilon_{o} c E_{0}^{2}$
$\mathrm{E}_{0}=\sqrt{\frac{2 \mathrm{I}}{\epsilon_{0} \mathrm{c}}}$ or $\sqrt{\frac{2 \times 500 \times 10^{9} \times 36 \pi}{\pi \times 3 \times 10^{8}}}$
$\mathrm{E}_{0}=2 \sqrt{3} \times 10^{2} \mathrm{\,N} / \mathrm{C}$
Standard 12
Physics
