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Phy107Spr06Lect34(HE3Rev)

# Phy107Spr06Lect34(HE3Rev) - Hour Exam 3 Review Quantum...

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1 Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 1 Hour Exam 3 Review • Hour Exam 3 : Wednesday, Apr. 19 • In-class (2241 Chamberlin Hall) • Twenty multiple-choice questions • Will cover: Basic Quantum Mechanics Uses of Quantum Mechanics Addl. Lecture Material Symmetry, solids, superconductivity The nucleus, fission & fusion • This is Lectures 22-33 • You should bring Your student ID 1 page notes, written double sided Calculator Pencil for marking answer sheet Mon office hours rescheduled to Tues. 11-12:15 Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 2 Quantum Mechanics • Quantization of light – Light comes in discrete clumps (photons) – Light shows both particle and wave-like properties – Photon energy E = hf=hc/ λ • Matter waves – Matter shows both particle and wave-like properties – Evidence for wave properties is interference and diffraction deBroglie wavelength = Planck's constant momentum Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 3 Photoelectric effect summary • Light is made up of photons, individual ‘particles’, each with energy hf One photon collides with one electron - knocks it out of metal. • If photon doesn’t have enough energy, cannot knock electron out. • Intensity ( = # photons / sec) doesn’t change this. = hc " = 1240 eV # nm Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 4 Photoelectric effect question A scientist is trying to eject electrons from a metal by shining a light on it, but none are coming out. To eject electrons, she should change the light by… A. decreasing the frequency B. increasing the frequency C. increasing the intensity D. increasing the wavelength Minimum frequency (maximum wavelength) required to eject electron Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 5 Compton scattering Collision of photon and electron in vacuum Photon loses energy, transfers it to electron Photon loses momentum transfers it to electron Total energy and momentum conserved Before collision After collision Photon energy E = hf Photon mass = 0 Photon momentum p = E / c Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 6 Compton scattering question A green photon collides with a stationary electron. After the the collision the photon color is A. unchanged B. shifted toward red C. shifted toward blue Photon transfers energy to electron. Photon energy goes down, so photon wavelength gets longer

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2 Mon. Apr 17, 2006 Phy107 Hour Exam 3 Review 7 Topic: Wave properties of matter • All objects show both wave-like properties and particle-like properties. • Electromagnetic radiation (e.g. light) shows interference effects (wave-like properties), but also comes in discrete photons of energy hf (particle-like properties) • Matter clearly shows particle-like properties, but also shows interference and diffraction effects (wave-like properties).
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Phy107Spr06Lect34(HE3Rev) - Hour Exam 3 Review Quantum...

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