A parallel beam of light of wavelength $$900 \mathrm{~nm}$$ and intensity $$100 \,\mathrm{Wm}^{-2}$$ is incident on a surface perpendicular to the beam. The number of photons crossing $$1 \mathrm{~cm}^{2}$$ area perpendicular to the beam in one second is :
- A$$3 \times 10^{16}$$
- B$$4.5 \times 10^{16}$$
- C$$4.5 \times 10^{17}$$
- D$$4.5 \times 10^{20}$$
✓ Correct answer: B
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