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NEET2012PhysicsDual Nature of MatterActual

A 200 ~W sodium street lamp emits yellow light of wavelength 0.6 m . Assuming it to be 25 % efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

Options

  1. A1.5 10²⁰
  2. B6 10¹⁸
  3. C62 10²⁰
  4. D3 10¹⁹

Correct answer

A. 1.5 10²⁰

Step-by-step solution

Efficient power P= N t h c =200 0.25 aligned & N t =50 h c & = 50 0.6 10⁻⁶ 6.6 10⁻³⁴ 3 10^8 & =1.5 10²⁰ aligned

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