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**Unformatted text preview: **PHYS-1200 PHYSICS II SPRING 2006 HOMEWORK SOLUTIONS CLASS 22. 38.10, 38.19, 38.28; Q38.09, Q38.13 38.10. a) The rate of solar energy (or solar power) that strikes the panel is, P = IA = (1.39 kW/m²)(2.60 m²) P = 3.61 kW b) The rate at which solar photons are absorbed by the panel is, m/s) 10 s)(3.0 J 10 (6.63 m) 10 W)(550 10 61 . 3 ( 8 34 9 3 × ⋅ × × × = = = =-- hc P hf P E P R photon λ R = 9.98 ×10 21 s-1 c) Avogadro’s number is the number of photons in one mole, so the time to collect one mole of photons is, 1- 21 23 s 10 98 . 9 10 02 . 6 × × = = R N t A t = 60.3 s 38.19. a) K max = hf – φ = eV 20 . 4 m 10 00 2 m/s) 10 s)(3.0 eV 10 (4.14 9 8 15- × × ⋅ × =--- φ λ hc K max = 2.01 eV b) The least energetic electron that escapes has just enough energy to get out, so it has no kinetic energy. K min = c) The stopping potential is given by, eV = K max . So, C 10 1.6 J/eV) 10 eV)(1.6 01 . 2 ( 19 19 max-- × × = = e K V V = 2.01 V d) The cutoff wavelength is given by,...

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