Determine what is the work function of the photocathode

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Image intensifiers used in night-vision devices create a bright image from dim light by letting the light first fall on a photocathode. Electrons emitted by the photoelectric effect are accelerated and then strike a phosphorescent screen, causing it to glow more brightly than the original scene. Recent devices are sensitive to wavelengths as long as 900 nm, in the infrared:

Part A: If the threshold wavelength is 900 nm, what is the work function of the photocathode?

Part B:If light of wavelength 640nm strikes such a photocathode, what will be the maximum kinetic energy, in eV, of the emitted electrons?

Reference no: EM13339360

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