HW14%20solutions

HW14%20solutions - Homework 14 solutions Physics 204,...

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Homework 14 solutions Physics 204, morning summer 2008 Chapter 29 Problems 8,21,38,43 Chapter 30 Problems 18,15 8. REASONING AND SOLUTION The work function of the material (using λ = 196 nm) is found from W 0 = hf = hc / = 1.01 × 10 –18 J The maximum kinetic energy of the ejected electron is (using = 141 nm) KE max = hf W 0 = hc / W 0 = 3.96 × 10 –19 J The speed of the electron is then v m == × × 2 2 3 96 10 932 10 19 5 KE J 9.11 10 kg m/s max 31 ch . . 21. REASONING AND SOLUTION The de Broglie wavelength is given by Equation 29.8 as = h / p , where p is the magnitude of the momentum of the particle. The magnitude of the momentum is p = mv , where m is the mass and v is the speed of the particle. Using this expression in Equation 29.8, we find that = ×⋅ ×× h mv v h m or 6.63 10 J s 1.67 10 kg 0.282 10 m 141 10 m s –34 –27 –9 3 . / 38. REASONING The energy of a photon of frequency f is, according to Equation 29.2, Eh f = , where h is Planck's constant. Since the frequency and wavelength are related by fc = / (see Equation 16.1), the energy of a photon can be written in terms of the wavelength as c = / . These expressions can be solved for both the wavelength and the frequency.
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HW14%20solutions - Homework 14 solutions Physics 204,...

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