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KCET2023PhysicsDual Nature of Matter

A 60 ~W source emits monochromatic light of wavelength 662.5 ~nm . The number of photons emitted per second is

Options

  1. A5 10¹⁷
  2. B2 10²⁰
  3. C5 10²⁶
  4. D2 10²⁹

Correct answer

B. 2 10²⁰

Step-by-step solution

Given, P=60 ~W =662.5 ~nm =6.625 10⁻⁷ ~m Energy of 1 photon =h v=h c = 6.625 10⁻³⁴ 3 10^8 6.625 10⁻⁷ =3 10⁻¹⁹ ~J Number of photons emitted per second aligned & = Power of source Energy of one photon & = 60 3 10⁻¹⁹ & =20 10¹⁹ & =2 10²⁰ aligned

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