At 510 nm, the wavelength of utmost sensitivity of the human eye, the dark-adapted eye can experience a 100 ms long flash of light of net energy 4.0 times 10^-17 J. (Weaker flashes of light might be detected, however not reliably.)
If 60% of the incident light is lost to reflection and absorption through tissues of the eye, determine how many photons attain the retina from this flash?
Deduce your answer in photons.