A parallel beam of light of wavelength 900nm and intensity 100Wm−2 is incident on a surface perpendicular to the beam. The number of photons crossing 1cm2 area perpendicular to the beam in one second is
Held on 26 Jul 2022 · Verified 6 Jul 2026.
3×1016
4.5×1016
4.5×1017
4.5×1020
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