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JEE Main 202117 MarchMorning Shift
Exam
JEE Main
Year
2021
Date
17 March
Shift
Morning Shift
Subject
Physics
Chapter
Electromagnetic Waves

JEE Main 2021 · 17 March · Morning Shift · Physics · Electromagnetic Waves

If 2 . 5 × 10 ^ - 6 N average force is exerted by a light wave on a...

If 2.5×10−6N2 . 5 \times {10}^{- 6}N average force is exerted by a light wave on a non-reflecting surface of 30cm230{cm}^{2} area during 40min40min of time span, the energy flux of light just before it falls on the surface is _______ Wcm−2.W{cm}^{- 2} .(Round off to the Nearest Integer), (Assume complete absorption and normal incidence conditions are there)

Correct answer

0

Step-by-step solution

F=IAcF = \dfrac{IA}{c}

⇒I=FcA=2.5×10−6×3×10830=25Wcm−2⇒ I = \dfrac{Fc}{A} = \dfrac{2 . 5 \times {10}^{- 6} \times 3 \times {10}^{8}}{30} = 25W{cm}^{- 2}

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