Exposure to a sufficient quantity of ultraviolet light will redden the skin, producing erythema—a sunburn. The amount of exposure necessary to produce this reddening depends on the wavelength. For a 1.0 cm2 patch of skin, 3.7 mJ of ultraviolet light at a wavelength of 254 nm will produce reddening; at 300 nm wavelength, 13 mJ are required.a. What is the photon energy corresponding to each of these wavelengths?b. How many total photons does each of these exposures correspond to?c. Explain why there is a difference in the number of photons needed to provoke a response in the two cases.
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Recoil Velocity
The amount of backward thrust or force experienced by a person when he/she shoots a gun in the forward direction is called recoil velocity. This phenomenon always follows the law of conservation of linear momentum.
Exposure to a sufficient quantity of ultraviolet light will redden the skin, producing erythema—a sunburn. The amount of exposure necessary to produce this reddening depends on the wavelength. For a 1.0 cm2 patch of skin, 3.7 mJ of ultraviolet light at a wavelength of 254 nm will produce reddening; at 300 nm wavelength, 13 mJ are required.
a. What is the photon energy corresponding to each of these wavelengths?
b. How many total photons does each of these exposures correspond to?
c. Explain why there is a difference in the number of photons needed to provoke a response in the two cases.
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