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A laser emits a pulse of light that lasts 10 ns. The light has a wavelength of 690 nm, and each pulse has an energy of 480 mJ. How many photons are emitted in each pulse? c = 3.0 x 10^8 m/s, h = 6.626 x 10^-34 s.
A metal surface has a work function of 2.50 eV. What is the longest wavelength of light that will eject electrons from the surface? Provide the answer in whole numbers with three digits and units (e.g. 777 nm).