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

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A 200 W sodium street lamp emits yellow light of wavelength 0.6 μ m . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second isNEET 2012 (Screening)

TestHub · Accepted Answer

Efficient power P = t N ​ × λ h c ​ = 200 × 0.25 ​ t N ​ = 50 × h c λ ​ = 6.6 × 1 0 − 34 × 3 × 1 0 8 50 × 0.6 × 1 0 − 6 ​ = 1.5 × 1 0 20 ​

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