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1218_Physics ProblemsTechnical Physics

1218_Physics ProblemsTechnical Physics - Chapter 43 Section...

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Chapter 43 559 Section 43.6 Electrical Conduction in Metals, Insulators, and Semiconductors P43.36 (a) E g = 1 14 . eV for Si hf = = × = × 1 14 1 14 1 60 10 1 82 10 19 19 . . . . eV eV J eV J a f e j so f × 2 75 10 14 . Hz (b) c f = λ ; λ µ = = × × = × = c f 3 00 10 2 75 10 1 09 10 1 09 8 14 6 . . . . m s Hz m m (in the infrared region) P43.37 Photons of energy greater than 2.42 eV will be absorbed. This means wavelength shorter than λ = = × × × × = hc E 6 626 10 3 00 10 2 42 1 60 10 514 34 8 19 . . . . J s m s J nm e je j . All the hydrogen Balmer lines except for the red line at 656 nm will be absorbed. P43.38 E hc g = = × × × λ 6 626 10 3 00 10 650 10 1 91 34 8 9 . . . J s m s m J eV e je j P43.39 If λ × 1 00 10 6 . m, then photons of sunlight have energy E hc = × × × × F H G I K J = λ max . . . . 6 626 10 3 00 10 1 00 10 1 1 24 34 8 6 19 J s m s m eV 1.60 10 J eV e je j . Thus, the energy gap for the collector material should be E g 1 24 . eV . Since Si has an energy gap E g 1 14 . eV, it will absorb radiation of this energy and greater. Therefore, Si is acceptable as a material for a solar collector. P43.40 If the photon energy is 5.5 eV or higher, the diamond window will absorb. Here,
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