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NEET 2021 · Photons: Energy, Momentum & Radiation Pressure

Photons: Energy, Momentum & Radiation Pressure question from NEET 2021

Q26NEET 2021Easy

Photons: Energy, Momentum & Radiation Pressure

The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600nm, when it delivers the power of 3.3 ×\times 10−-3 watt will be: (h = 6.6 ×\times 10−-34 Js)

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Answer: (d)

  1. E=hcλ=(6.6×10−34)(3×108)6×10−7=3.3×10−19 JE = \frac{hc}{\lambda} = \frac{(6.6 \times 10^{-34})(3 \times 10^{8})}{6 \times 10^{-7}} = 3.3 \times 10^{-19}\text{ J}
  2. n=PE=3.3×10−33.3×10−19=1016 s−1n = \frac{P}{E} = \frac{3.3 \times 10^{-3}}{3.3 \times 10^{-19}} = 10^{16}\text{ s}^{-1}
  3. So the answer is (d) 101610^{16}.
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