JEE Mains · Physics · STD 12 - 11. Dual nature of radiation and matter
Average force exerted on a non-reflecting surface at normal incidence is \(2.4 \times 10^{-4} \mathrm{~N}\). If \(360 \mathrm{~W} / \mathrm{cm}^2\) is the light energy flux during span of \(1\) hour \(30\) minutes. Then the area of the surface is _______.
- A \(0.2 \mathrm{~m}^2\)
- B \(0.02 \mathrm{~m}^2\)
- C \(20 \mathrm{~m}^2\)
- D \(0.1 \mathrm{~m}^2\)
Answer & Solution
Correct Answer
(B) \(0.02 \mathrm{~m}^2\)
Step-by-step Solution
Detailed explanation
\(\text { Pressure }=\frac{I}{C}=\frac{F}{A}\) \(\Rightarrow \frac{360}{10^{-4} \times 3 \times 10^8}=\frac{2.4 \times 10^{-4}}{A}\) \(\Rightarrow A=2 \times 10^{-2} \mathrm{~m}^2=0.02 \mathrm{~m}^2\)
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