123Cex3verCsol - Name Student ID Score last first Physics...

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Unformatted text preview: Name ___________________________________ Student ID ____________ Score_______ last first Physics 123C, Spring 09, Version C Exam 3, page 1 I. Matter Waves A beam of neutrons (rest mass 1 . 675 × 10-27 kg) of kinetic energy 9 . 00 × 10-16 J strikes a diffraction grating. Assume that the grating slits are very small (sub- atomic-sized) dimension in the horizontal width, but macroscopic (about 2 mm) in the vertical dimension. 1. (5 pts) Which choice best represents the deBroglie wavelength of these neutrons? 2 . 21 × 10-10 m 1 . 32 × 10-13 m 1 . 87 × 10-13 m 3 . 82 × 10-13 m 2 . 62 × 10 12 m A B C D E 2. (5 pts) Which choice best represents a physics law or principle that could be used to explain why a neutron does not follow a straight path through the grating to the screen? A. Conservation of Energy. B. Heisenberg Uncertainty Principle. C. Stefan-Boltzmann Radiation Law. D. Planck’s Quantization Principle. E. Conservation of Angular Momentum. Useful Data: h = 6 . 63 × 10-34 J ∏ s 1 . 000 eV = 1 . 602 × 10-19 J Pattern on screen White = many neutrons ' Incoming neutrons Diffraction grating Screen Pattern on screen White = many neutrons ' Incoming neutrons Screen Name ___________________________________ Student ID ____________ Score_______ last first Physics 123C, Spring 09, Version C Exam 3, page 2 II. Photons Electromagnetic radiation of wavelength λ strikes a metal plate, and the maximum kinetic energy of ejected electrons is found to be 2 . 80 eV. The work function for this metal is known to be W = 1 . 50 eV. 3. (4 pts) Which choice best represents the threshold frequency for electron photoemission from this metal? 3 . 5x10 33 Hz 9 . 2x10 14 Hz 3 . 6x10 14 Hz 5 . 6x10 14 Hz 6 . 0x10 14 Hz A B C D E 4. (4 pts) Which choice best represents the wavelength λ of the incident radiation? 289 nm 327 nm 443 nm 828 nm 955 nm A B C D E 5. (4 pts) Which choice best represents other possible values of electron kinetic energy that might be obtained using this metal plate and light of this wavelength?...
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123Cex3verCsol - Name Student ID Score last first Physics...

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