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Unformatted text preview: Figure 39-28 Lehigh University April 8, 2008 Physics 21, Spring 2008 Home Work Assignment (27-28) Note: Solutions to the problems must be submitted on WileyPLUS (www.wileyplus.com). HW-27 due April 22 27-1. (HRW 38-7) An ultraviolet lamp emits light of wavelength 400 nm at the rate of 400 W An infrared lamp emits light of wavelength 700 nm, also at the rate of 400 W (a) Which lamp emits photons at the greater rate and (b) what is that greater rate? 27-2. (HRW 38-11) A 100 W sodium lamp radiates energy uniformly in all directions. (a) At what rate are photons emitted by the lamp? (b) At what distance from the lamp will a totally absorbing screen absorb photons at the rate of 1.00 photon/cm 2 s? (c) What is the photon flux (photons per unit area per unit time) on a small screen 2.00 m from the lamp? 27-3. (HRW 38-19) The stopping potential for electrons emitted from a surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping wavelength 491 nm is 0....
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