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A 2.0 mW source emits photons of 3.98 × 10⁻¹⁹ J each. How many per second?
A5.0 × 10¹²
B5.0 × 10¹⁵
C2.0 × 10¹⁸
D8.0 × 10⁻¹⁷
Answer & Solution
Correct answer: B. 5.0 × 10¹⁵
N = P/E = 2.0 × 10⁻³ W divided by 3.98 × 10⁻¹⁹ J gives about 5.0 × 10¹⁵ photons per second.
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