Sun light falls normally on a surface of area $36 \mathrm{~cm}^{2}$ and exerts an average force of $7.2 \times 10^{-9} \mathrm{~N}$ within a time period of 20 minutes. Considering a case of complete absorption, the energy flux of incident light is
Solution
<p>Pressure $= {l \over c}$</p>
<p>$\Rightarrow {F \over A} = {l \over c}$</p>
<p>$$ \Rightarrow l = {{7.2 \times {{10}^{ - 9}} \times 3 \times {{10}^8}} \over {36 \times {{10}^{ - 4}}}}$$ W/m<sup>2</sup></p>
<p>$= 600$ W/m<sup>2</sup></p>
<p>$\Rightarrow l = 0.06$ W/cm<sup>2</sup></p>
About this question
Subject: Physics · Chapter: Electromagnetic Waves · Topic: Maxwell's Equations
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