Lasers are now used in eye surgery. Given that the wavelength of a certain laser is 514 nm and the power of the laser is 1.9 W, how many photons are released if the laser is used for 0.052 s during the surgery? HELP: You know the energy released per second (the power) and the time the laser is on - from this you can calculate the total energy released. HELP: You also know the wavelength of each photon and can therefore calculate the energy of each photon. Knowing the total energy and the energy of each individual photon leads you to the number of photons!