Published on October 16, 2007
Slide1: Please be Seated Physics is PhunNovember 2005: Physics is Phun November 2005 Einstein and the 2005 Year of Physics In 1905, at the age of 25,Einstein published papers on Brownian Motion, the Photoelectric Effect, and Relativity.: In 1905, at the age of 25, Einstein published papers on Brownian Motion, the Photoelectric Effect, and Relativity. This achievementhas been called the most productive yearfor any scientist,ever.: This achievement has been called the most productive year for any scientist, ever. The centennialof this eventis celebrated as the2005 Year of Physics: The centennial of this event is celebrated as the 2005 Year of Physics Quote of the Century:"The word ‘genius’ isn'tapplicable in football. A geniusis a guy like Norman Einstein."--Joe Theismann, NFL footballquarterback & sports analyst.: Quote of the Century: "The word ‘genius’ isn't applicable in football. A genius is a guy like Norman Einstein." --Joe Theismann, NFL football quarterback & sports analyst. Slide7: In the matter of physics, the first lessons should contain nothing but what is experimental and interesting to see. A pretty experiment is in itself often more valuable than twenty formulae extracted from our minds. -Albert Einstein Some Reference materials:National Science Foundation web siteAmerican Association of Physics Teachers web siteUniversity of Maryland Physics Question of the Week web site: Some Reference materials: National Science Foundation web site American Association of Physics Teachers web site University of Maryland Physics Question of the Week web site Slide9: Topics for this evening: Brownian Motion The Photoelectric Effect Relativity Slide10: Brownian motion: is the small molecular motion inherent in all molecules, even at the lowest possible temperature. Discovered by botanistRobert Browne (1773-1858)“..in 1827. The story goes that Brown was studying pollen particles floating in water under the microscope.” : Discovered by botanist Robert Browne (1773-1858) “..in 1827. The story goes that Brown was studying pollen particles floating in water under the microscope.” From Wikipedia, the free encyclopedia. Brownian Motionof smoke particlesdemonstration: Brownian Motion of smoke particles demonstration Java appletofBrownian motion: Java applet of Brownian motion Mechanical ModelofBrownian Motion: Mechanical Model of Brownian Motion Slide15: “More accurate” description: statistical fluctuations requiring ~10,000 net molecular collisions to change particle motion. Implications ofBrownian Motion:: Implications of Brownian Motion: Air pressure Diffusion of gases Reducing Brownian Motion: Reducing Brownian Motion Minimizing molecular motion in atomic clocks increases accuracy of clocks and GPS. Slide18: William Phillips Professor of Physics, University of Maryland Nobel prize in 1997 for Laser cooling of atoms Video showing magnetically trapped block of cesium atoms Slide19: The Photoelectric Effect: describes the particle behavior of light. Einstein received the 1921 Nobel Prize in Physicsfor work on thePhotoelectric Effect: Einstein received the 1921 Nobel Prize in Physics for work on the Photoelectric Effect Ef = h fE = photon energyh = Planck’s constant (~6.6x10-34 Joule-sec)f = light frequency: Ef = h f E = photon energy h = Planck’s constant (~6.6x10-34 Joule-sec) f = light frequency Slide23: KEe = Ef – W = hf - W A single photon of light is absorbed by an electron, causing it to be ejected from the surface of the metal. Graphic from Wikipedia, the free encyclopedia. Demonstrations: Demonstrations Photoelectric effect in zinc 2. Full photoelectric effect Applications:: Applications: Solar power Solar engines Solar switches “Hydrogen” economy 2005 Nobel prizein Physics toGlauber, Hall, & Haensch(application of quantum nature of light to build atomic clocks to 10-15 accuracy and thus improve GPS accuracy ): 2005 Nobel prize in Physics to Glauber, Hall, & Haensch (application of quantum nature of light to build atomic clocks to 10-15 accuracy and thus improve GPS accuracy ) Slide27: Relativity: deals in part with frames of reference and how we view physical phenomena. Slide28: Physics experiments are fully accurate only in an inertial frame of reference or in a local inertial frame. When might a physics experiment be correct? Galilean Relativityand theFunnel Cart Demonstration: Galilean Relativity and the Funnel Cart Demonstration Local inertialframe of referencedemonstration: Local inertial frame of reference demonstration Einstein’sfavorite demonstration: Einstein’s favorite demonstration The Speed of Lightand the search for aPreferred Inertial Frame of Reference: The Speed of Light and the search for a Preferred Inertial Frame of Reference TheMichelson-Morleyexperiment: The Michelson-Morley experiment Slide34: 1. There is NO preferred frame of reference. 2. Thespeed of Lightis the same in allinertial frames: 2. The speed of Light is the same in all inertial frames Applicationsof Relativity: Applications of Relativity Michelson Interferometerwith White Light Color Mixing:W = R + G + BW – R = G + B = CW – G = R + B = MW – B = R + G = Y: Michelson Interferometer with White Light Color Mixing: W = R + G + B W – R = G + B = C W – G = R + B = M W – B = R + G = Y Slide38: Michelson Interferometer setup using White Light Michelson InterferometerwithWhite Light: Michelson Interferometer with White Light Slide40: Michelson Interferometer with White Light Full motion of mirror for this video ~10 μ = 0.000,010m = 0.01 mm Slide41: We are on the web at http://www.physics.umd.edu/lecdem/ Animated Gifs compliments of bellsnwhistles.com The End See you in January!