If you want to know your progress so far, please send me an email request [email protected] III review (transparences)Lightning ReviewAn x-ray photon is scattered by an electron. The frequency of the scattered photon relative to that of the incident photon (aA photon of energy E0 strikes a free electron, with the scattered photon of energy E moving in the direction opposite that of27.8 Photons and Electromagnetic Waves28.9 Wave Properties of ParticlesThe Davisson-Germer ExperimentReview problem: the wavelength of a protonA non-relativistic electron and a non-relativistic proton are moving and have the same de Broglie wavelength. Which of the foIf you want to know your progress so far, please send me an email request [email protected]/16/200311/16/2003General Physics (PHY 2140)Lecture 28Lecture 28¾ Modern Physics9Quantum Physics9Photons. Wave properties of particlesChapter 27http://www.physics.wayne.edu/~apetrov/PHY2140/2211/16/200311/16/2003If you want to know If you want to know your progressyour progressso far, please so far, please send me send me an email requestan email [email protected]@physics.wayne.edu3311/16/200311/16/2003Exam III review (transparences)Exam III review (transparences)4411/16/200311/16/2003Lightning ReviewLightning ReviewLast lecture:1.1.Quantum physicsQuantum physics99XX--raysrays99Compton scattering()1cosehmcλθ∆= −()minhceVλ=∆Compton scatteringReview Problem: The best color to paint a radiator, as far as heating efficiency is concerned, is1. black.2. white.3. metallic.4. some other color.5. It doesn’t really matter.5511/16/200311/16/2003QUICK QUIZ 1An x-ray photon is scattered by an electron. The frequency of the scattered photon relative to that of the incident photon (a) increases, (b) decreases, or (c) remains the same.(b). Some energy is transferred to the electron in the scattering process. Therefore, the scattered photon must have less energy (and hence, lower frequency) than the incident photon.6611/16/200311/16/2003QUICK QUIZ 2A photon of energy E0strikes a free electron, with the scattered photon of energy E moving in the direction opposite that of the incident photon. In this Compton effect interaction, the resulting kinetic energy of the electron is (a) E0 , (b) E , (c) E0− E , (d) E0 + E , (e) none of the above.(c). Conservation of energy requires the kinetic energy given tothe electron be equal to the difference between the energy of the incident photon and that of the scattered photon.7711/16/200311/16/200327.8 Photons and Electromagnetic Waves27.8 Photons and Electromagnetic WavesLight has a dual nature.Light has a dual nature.It exhibits both wave and particle It exhibits both wave and particle characteristicscharacteristicsApplies to all electromagnetic radiationApplies to all electromagnetic radiationThe The photoelectric effectphotoelectric effectand and Compton scatteringCompton scatteringoffer evidence for offer evidence for the the particle nature of lightparticle nature of lightWhen light and matter interact, light behaves as if it were compWhen light and matter interact, light behaves as if it were composed of osed of particlesparticlesInterferenceInterferenceand and diffractiondiffractionoffer evidence of the offer evidence of the wave nature of lightwave nature of light8811/16/200311/16/200328.9 Wave Properties of Particles28.9 Wave Properties of ParticlesIn 1924, Louis de Broglie postulated that In 1924, Louis de Broglie postulated that because because photons have wave and particle characteristics, perhaps photons have wave and particle characteristics, perhaps all forms of matter have both propertiesall forms of matter have both propertiesFurthermore, the frequency and wavelength of matter Furthermore, the frequency and wavelength of matter waves can be determinedwaves can be determinedThe The de de BroglieBrogliewavelengthwavelengthof a particle isof a particle isThe frequency of matter waves ismvh=λThe frequency of matter waves ishEƒ =9911/16/200311/16/2003The DavissonThe Davisson--Germer ExperimentGermer ExperimentThey scattered lowThey scattered low--energy electrons from a nickel targetenergy electrons from a nickel targetThey followed this with extensive They followed this with extensive diffraction measurementsdiffraction measurementsfrom from various materialsvarious materialsThe wavelength of the electrons calculated from the diffraction The wavelength of the electrons calculated from the diffraction data data agreed with the expected de Broglie wavelengthagreed with the expected de Broglie wavelengthThis confirmed the wave nature of electronsThis confirmed the wave nature of electronsOther experimenters have confirmed the wave nature of other Other experimenters have confirmed the wave nature of other particlesparticles101011/16/200311/16/2003Review problem: the wavelength of a protonReview problem: the wavelength of a protonCalculate the de Calculate the de BroglieBrogliewavelength for a proton (mwavelength for a proton (mpp=1.67x10=1.67x10--2727kg ) kg ) moving with a speed of 1.00 x 10moving with a speed of 1.00 x 1077m/sm/s..111111/16/200311/16/2003Calculate the de Calculate the de BroglieBrogliewavelength for a proton (mwavelength for a proton (mpp=1.67x10=1.67x10--2727kg ) moving with a kg ) moving with a speed of 1.00 x 10speed of 1.00 x 1077m/sm/s..Given the velocity and a mass of the proton we can compute its wavelengthGiven:v = 1.0 x 107m/sFind:λp= ?pphmvλ=Or numerically,()()()341431 76.63 103.97 101.67 10 1.00 10psJsmkg m sλ−−−×⋅==×××121211/16/200311/16/2003QUICK QUIZ 3A non-relativistic electron and a non-relativistic proton are moving and have the same de Broglie wavelength. Which of the following are also the same for the two particles: (a) speed, (b) kinetic energy, (c) momentum, (d) frequency?(c). Two particles with the same de Broglie wavelength will have the same momentum p = mv. If the electron and proton have the same momentum, they cannot have the same speed because of the difference in their masses. For the same reason, remembering that KE = p2/2m, they cannot have the same kinetic energy. Because the kinetic energy is the only type of energy an isolated particle can have, and we have argued that the particles have different energies, Equation 27.15 tells us that the particles do not have the same frequency.131311/16/200311/16/2003If you want to know If you want to know your progressyour