MEDIUMMCQ SINGLEJEE Mains ChemistryPhysical ChemistryAtomic StructureIntro

The number of photons emitted in 10 hours by a 60 W sodium lamp (λ = 6000 Å) is approximately

0.6.50 × 10²⁴

1.6.40 × 10²³

2.8.40 × 10²³

3.3.40 × 10²³

Explanation

Total energy = 60 W × 10 × 3600 s = 2,160,000 J. Energy per photon = hc/λ = 2 × 10⁻²⁵/6000 × 10⁻¹⁰ = 3.32 × 10⁻¹⁹ J. n = 2,160,000/3.32 × 10⁻¹⁹ ≈ 6.50 × 10²⁴

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