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JEE Main 2025 (3 Apr, Shift 1) · Photons: Energy, Momentum & Radiation Pressure

Photons: Energy, Momentum & Radiation Pressure question from JEE Main 2025 (3 Apr, Shift 1)

Q9JEE Main 2025 · 3 APR · SHIFT 1Medium

Photons: Energy, Momentum & Radiation Pressure

The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2 m away from it, is

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Answer: (d)

  1. Intensity at r=2 mr = 2\text{ m}: I=P4πr2=4504π×4≈8.95 W/m2I = \dfrac{P}{4\pi r^2} = \dfrac{450}{4\pi\times4} \approx 8.95\text{ W/m}^2
  2. Perfect reflector: prad=2Ic=2×8.953×108p_{rad} = \dfrac{2I}{c} = \dfrac{2\times8.95}{3\times10^{8}}
  3. prad≈6×10−8 Pap_{rad} \approx 6\times10^{-8}\text{ Pa}
  4. So the answer is (d) 6×10−86\times10^{-8} Pascals.
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