Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec on the average at a target irradiated by this beam is:

Question

Dr. Abubacker · Accepted Answer

[Solution from source] Energy per photon = hc/λ = (6.63 × 10⁻³⁴ × 3 × 10⁸)/(667 × 10⁻⁹) ≈ 2.98 × 10⁻¹⁹ J. Photons per second = 9 × 10⁻³/2.98 × 10⁻¹⁹ ≈ 3 × 10¹⁶. Forgetting the milli prefix gives 3 × 10¹⁹. Answer (1).

Q. Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec on the average at a target irradiated by this beam is:

Explanation

Reviewed by Dr. Abubacker

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