Essay About Sound Waves And Light Wavesp Waves

Physics Sg Lab Report
Doppler effect: observer behind source hears lower pitch (longer wavelength)[pic 1]                     observer in front of source hears higher pitch (shorter wavelength) sound waves are more commonly shifted than light wavesp waves- fastest of 3 (longitudinal, pressure, can go through liquid) s waves- 1/2 as fast as ^ (transverse, secondary, can’t go through liquid) L waves- slowest of 3 (combo, L= s + p) its amplitude determines the Richter magnitude of an earthquake L = travel on surface // S and P travel on surface OR undergroundcategorized in different ways: how they travel matter or mechanical waves- must move through substances/ material (like earthquakes) energy or electromagnetic waves- can pass through a vacuum (light, heat) how they’re generatedlongitudinal- parallel// matter waves// sound + shock waves// can propagate in solids, liquids, & gasestransverse- perpendicular// energy waves// all forms of electromagnetic radiation (gamma, UV, when a crowd does the wave)// can propagate only in solidstransmission medium- what wave passes through (earthquake=ground; music= air) determines speed of waveinterference does not destroy the component waves. they mix, un-mix, and continue (ex. headlights)incident wave enters at the same angle that reflected wave bounces offhigh impedance = out of phase = most energy bounces backCh 14all sounds are caused by a vibration of some kind and speed of sound is generally greatest in solidssound waves in gases and liquids are primarily longitudinalsound waves in solids can have both transverse and longitudinal components bc intermolecular interaction in solids are much stronger// solids > liquids > gases in elasticitynodes- points of completely destructive interferenceantinodes- points of completely constructive interference standing waves- other waves transmit energy not matter// this doesnt transmit energy or momentumpure standing waves are formed by only 2 things: tuning fork and electronic keyboard// has a patternnoise is different from standing wave bc there is no patternsympathetic vibration- an oscillation induced in an object by indirectly driving at its fundamental frequencyconditions for resonance: the wavelength must have a whole number of wave segments fit on the string segments- the portion of the string between adjacent nodeswhen string is plucked in middle it vibrates at natural frequency (lowest freq that can sustain a standing wave)fundamental frequency = resonant = natural = 1st Harmonic// things can have more than 1 natural frequencyamplitude = loudness// frequency = pitch/ noteaudible region = 20 – 20k Hz// there is a limit in the sound spectrum (one gigahertz) frequencies lower than 20 = infrasonic range (ie. nature, earthquakes)higher than 20k = ultrasonic// can travel for km in water so used in sonar// (ie. crystals, seafloor imaging) audibility threshold- quietest sound you can hear// pain threshold- loudest sound not producing painintensity- the amount of energy entering an area in a certain amount of timeintensity level- comparison of a sound’s loudness to a standard (that standard = audibility threshold) both the loudness AND duration of a sound affect hearing losssonic boom- when something’ s traveling at speed of sound, a large # of waves overlap & produce many points of constructive interference which form a shock wave & when the shock wave passes over someone, the large concentration of energy produces a sonic boom// doesnt only occur when plane breaks sound barrierMach- number greater than one indicates supersonic speed and less than one indicates subsonic. Number 2 indicates a speed twice the speed of sound