week5

# week5 - Light is a wave phenomenon This is not obvious —...

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Unformatted text preview: Light is a wave phenomenon This is not obvious — lsaac Newton treated light as particles, so you have a dichotomy ofwave phenomenon vs. particles [called photons] The appearance ofa particle and a wave seem to be totally different This concept is one ofthe bridges to modern physics Periodicity — key quality in waves Principle of Superposition - seen when talking about motion (keeping x component completely separate from y component] 0 lfyou add waves together when they are exactly lined up, you’ll get a wave that‘s twice as high; ifthey’re not lined up, you’ll get two waves 0 This is superposition A 0 Wave phenomenon’s are so diverse that you can add them together that you get something called a wave packet I This is the wave / particle connection Interference pattern [waves do this, particles don’t] 0 In the 19005, people decided light showed wave phenomena [unlike 18003 with Newton saying light is made up of particles] 0 If light is made up of particles, how would you be able to get waves in patterns that cancel out? 0 Light almost has a split personality — when you do experiments to look for wave phenomena in light, you’ll find wave phenomena. But when you do an experiment to look for particle phenomena, you’ll find that. Diffraction — something that waves do and particles don’t Doppler effect [again waves and not particles) 0 When waves are compressed together, it’s a rising pitch 0 When crests are further apart, it’s a falling pitch Refraction — bending of light around an obstacle — also a wave phenomenon 0 Speed oflight in water is slower than in air Frequency — number ofwave patterns/forms that go by in one second Speed of wave = c 0 Relationship between c, lambda, and nu? I M) I U=?\/C ' K=C/v I u = cycles per second I k = meters standing waves — when waves are blocked offas if in a chamber 0 nodes — points that do not move light — electromagnetic radiation: oscillating electric and magnetic fields 0 shorter wavelength (7t) 9 higher frequency [U] 0 blue light has shorter wavelength than red light 0 ROYGBIV — I red = long A, low “u O I Violet = short A, high 1) X-rays — nothing different from optical light except it’s a much higher frequency Radio waves Microwaves Gamma waves — such a high frequency that’ it’s deadly Friday, 9/24 Classical physics — 18th,19Ch centuries; ° Newtonian mechanics I Electromagnetic theory I Thermodynamics O O O Developed by observing the properties ofbulk matter Particularly concerned with the “flow of energy” Heat a plays a huge role in thermodynamics I Heat is not really a form of energy...lt is a process that describes energy flow in thermal environments. I Aka. Heat -- Energy that r'flows” from one object to another because ofa temperature difference. Zeroth law — if object A is in thermal equilibrium with object B, and object B is in thermal equilibrium with object C, then object A is in thermal equilibrium with object C. I Thermal equilibrium — things are at the same temperature. It can be in a variety of energy states. °F 9 °C [F-32][5/9) “C 9 “F [C+32)(9/5] I There is an absolute limit to how far you go in temperature — 237.15°C Kelvin scale I No "degrees" Kelvin — it’s just Kelvin. I 100°C 2 boiling point = 373 K I 0° C = freezing point = 273 K I -273° : lowest 2 0 K First Law — conservation ofenergy I Change in internal energy ofa system is equal to the heat you put in minus the work done by the system ' {Change in energy] 2 [heat put in — work done] Second law — heat does not pass from a body at low temperature to one at high temperature without an accompanying change elsewhere. I heat travels from hot to cold, not cold to hot I log burning turns to ash...so why can’t you use that ash for more fire/energy? 0 Log burning is a high quality energy source, the ash is a low quality energy source ...
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week5 - Light is a wave phenomenon This is not obvious —...

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