Chapter 12: Wave motionSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Reflection and TransmissionTwo waves pulses pass each otherInterference of WavesTwo waves interfereStanding WavesSlide 17Slide 18Slide 19Slide 20Resonant waves in a cavitySlide 22Longitudinal standing wavesSpeed of sound in hydrogenSlide 25Slide 26Slide 27Slide 28RefractionSlide 30Slide 31Chapter 12: Wave motion )](sin[ t)(x, vxtAy MechanicalSoundLightRadio& TVEarthquakeswaterWavesThere are transverse, longitudinal, combined transverse longitudinal wavesSpeed of propagation is determined by mediumMaking wavesSpeed of sound v=350 m/sThe wave advances one wavelength during one period TfvTfTtimecedisv/1//tanvelocityWaveLengthFrequency340 m/s x 1/8 s=42.5 mMathematical description of a wave (wave on a string)Motion of x at an earlier time (t-x/v)Reflectionand SuperpositionWhat happens at the boundary?Encounter between waves travelling in opposite directions InvertedAt point 0 amplitude = 0IdenticalAt point 0 slope = 0End of rope is fixed End of rope is freeWave pulse reaches a discontinuityWave pulse is partly reflected and transmittedReflection and TransmissionTwo waves pulses pass each other destructiveconstructiveInterference of WavesConstructive DestructiveLight plus light gives darkness when Φ=180Two waves interfereconstructivelydestructivelypartially destructivelyStanding WavesThe frequency at which standing waves are produced are the natural frequencies or resonant frequenciesWhat is a flutter echo?Standing waves also happen in acousticsStanding waves and normal modesFormation of a standing wavewave traveling to the left(red)combines with wave traveling to the right(blue)to form a standing wave (brown)Standing waves and normal modeswavelengthsfrequenciesThese frequencies are harmonics or overtonesResonant waves in a cavity ------ 3 2, 1, n 2n Ln ------ 3 2, 1, n n2L n ------ 3 2, 1, n nf 2Lnv v f1nn  frequency l fundamenta 2Lv v f1 1Longitudinal standing wavesSpeed of sound in hydrogenSound, light and intensityExample 12.9 A bird singsRefraction atv al Sin atv al Sins Wave222111 Sin v SinvSoldiers 1 21 10 10 20 30 40 50 60 70 80 90 10005101520Number of StudentsGradeFall 2012 Phys201Exam#2Average=