4. Under most conditions, the human eye will respond to a flash of light if 100 photons hit photoreceptors at the back of the eye. Determine the total energy (in J and eV) of such a flash ifthe wavelength is 550 nm (green light). Check example 27-4 in the textbook, if you need help. 5. A silver surface (with work function of 4.7eV) is illuminated by a light of wavelength 222-nm. (a) Calculate the kinetic energy of an electron emitted from silver. Express this in eV. (b) Calculate the stopping potential. Check example 27-5 in the textbook, if you need help. 6. What wavelength photon would be required to ionize a hydrogen atom in the ground state and give the ejected electron a kinetic energy of 11.5 eV