/15 Show all your work for the following questions. Make sure to sho significant digits to receive full marks. 1. How many 550 nm green light photons per second are required to deliver 15W of power? (3) 2. Explain how stopping voltage is related to the maximum kinetic energy of an electron.(1) 3. What stopping potential will stop electrons of energy 9.5 X 10-19J. (2) 4. What is the momentum and energy of an ultraviolet wave of wavelength 6.8 X 10-10m? (3)