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Dual Nature of Radiation and Matter question

2012 · Q131
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Dual Nature of Radiation and Matter question

2012 · Q131

NEETPhysicsDual Nature of Radiation and MatterMCQ+4 / −1
A 200 W sodium street lamp emits yellow light of wavelength 0.6 μ\muμm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
  1. A
    1.5 ×\times× 1020
  2. B
    6 ×\times× 1018
  3. C
    62 ×\times× 1020
  4. D
    3 ×\times× 1019
View written solutionFree

Correct answer: A

Efficient power, P = Nt×hcλ{N \over t} \times {{hc} \over \lambda }tN​×λhc​

⇒\Rightarrow⇒ Nt{N \over t}tN​ = 25100×200(6.6×10−34)(3×108)0.6×10−6{{{{25} \over {100}} \times 200} \over {{{\left( {6.6 \times {{10}^{ - 34}}} \right)\left( {3 \times {{10}^8}} \right)} \over {0.6 \times {{10}^{ - 6}}}}}}0.6×10−6(6.6×10−34)(3×108)​10025​×200​ = 1.5 ×\times× 1020

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