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JEE Main 2022 (30 Jun, Shift 1) · Photons: Energy, Momentum & Radiation Pressure

Photons: Energy, Momentum & Radiation Pressure question from JEE Main 2022 (30 Jun, Shift 1)

Q20JEE Main 2022 · 30 JUN · SHIFT 1Easy

Photons: Energy, Momentum & Radiation Pressure

A source of monochromatic light liberates 9 ×\times 1020 photon per second with wavelength 600 nm when operated at 400 W. The number of photons emitted per second with wavelength of 800 nm by the source of monochromatic light operating at same power will be:

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Answer: (a)

  1. At the same power, n=Pλhc⇒n∝λn = \frac{P\lambda}{hc} \Rightarrow n \propto \lambda.
  2. n2=n1λ2λ1=9×1020×800600n_2 = n_1 \frac{\lambda_2}{\lambda_1} = 9 \times 10^{20} \times \frac{800}{600}
  3. n2=12×1020n_2 = 12 \times 10^{20} photons per second
  4. So the answer is (a).
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