Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is __________. [2026]

Question

Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is __________.

$(Given : h = 6.63 \times 10^{- 34} J \cdot s and 𝑐 = 3 \times 10^{8} m / s)$ [2026]

Smart Achievers · Accepted Answer

(1)

$P = \frac{n h c}{λ}$

$6 \times 10^{- 3} = \frac{n \times 6.63 \times 10^{- 34} \times 3 \times 10^{8}}{663 \times 10^{- 9}}$

$n = 2 \times 10^{16} photons$

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