CSEC Physics Lab - Sound wave interference and its variation with frequency
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The document investigates sound wave interference produced by two loudspeakers playing an identical sound, noting that the distance between loud and soft sounds decreases as the frequency of the audio signal increases. The procedure involved measuring distances of maximum and minimum sound as a student walked between the speakers, revealing patterns of constructive and destructive interference. Key findings showed that increasing frequency resulted in closer maxima and minima, supporting the relationship between frequency and sound wave behavior.
CSEC Physics Lab - Sound wave interference and its variation with frequency
- 1. Hypothesis: Alternatingloudandsoftsoundscanbe heardat a distance infrontof two loudspeakers playingthe same sound.The distance betweenthe loudandsoftsoundsdecreasesif the frequencyof the audiosignal generatorisincreased. Aim: To investigate soundwaveinterference andhow itvarieswithfrequency. Apparatus: Audiosignal generator,2loudspeakers,connectingwires,meterrule,chalk Diagrams: Procedure: 1. Two speakerswere connectedtoanaudiosignal generator. 2. The signal generatorwasstartedand adjustedtoemitidentical loudsoundsfromboth speakers. 3. A student,blockingone earwasallowedtostandinthe centerof the speakersata certain distance fromthem. 4. The studentwalkedparalleltothe speakersuntil the loudestsoundwasheard.Hisdistance away fromthe centerwas recorded. 5. The studentreturnedtothe centerand walkedinthe opposite directionuntil the loudest soundwasheard.The distance awayfromthe centerwas recorded. 6. Steps3-5 were repeated 4timesbuteach time the studentwalkedfurtherthanthe distance before until the maximumsoundwasheard. 7. Steps3-6 were repeatedbutnotingareasof the softestsoundinstead. 8. The frequencyof the generatorwasincreasedandsteps3-8 were repeatedwithout recordingthe distances.
- 2. Results: Constructive Interference – Regions of Maxima Distance Away From Center (cm) Average (cm) 21 19 20 42 38 40 58 62 60 80 80 80 99 97 98 Destructive Interference – Regions of Minima Distance Away From Center (cm) Average (cm) 10 10 10 29 31 30 48 52 50 68 72 70 88 94 91 Whenthe frequencywasincreasedthe areasof maximumandminimumsoundcorrespondingtothose recordedbefore were closertothe centerand closertoeach other.There were alsomore areas of maximumandminimumsoundalongthe same distance walkedasbefore. Analysis: Soundwavesare longitudinalandtravel bya seriesof compressionsandrarefactions. The speakersconvertedelectrical signalintovibrationscausingcompressionsandrarefactionsof air moleculesthusallowingsoundtotravel tothe student’sear.Byblockinganear the studentwasable to concentrate andallowthe soundto be heardfrom onlyone ear. The studentnotedvariousareasof loudand softsounds.Thisindicatesthatinterference was takingplace. The areasof maximumsound(maxima) were where constructive interference took place and the areasof minimumsound(minima) were wheredestructive interference tookplace. Constructive interference occurswhentwowavesthatare inphase combine toproduce a wave twice the amplitude of the original waves.Thiswaswhere compressionsoverlappedeachotherand rarefactionsoverlappedeachother.Destructive interference occurswhentwowavesthatare out phase cancel out eachother.Thiswas where compressionsoverlappedrarefactionandrarefactions overlappedcompressions.
- 3. The distance betweenthe areasof maximaandminimadecreasedwhenthe frequency was increased.Frequencyisthe numberof wavesproducedpersecond.Since more wavesare produced persecondthe wavesinterfere more frequently,thusproducingcloserareasof maximaandminima. The wavelengthof soundcouldbe calculatedfromthisexperiment.Usingone areaof constructive of destructive interference,itsdistance awayfromthe center(m),the angle the pathof maxima/minimamakeswiththe center(pheta) andthe distance betweenthe twospeakers(d),itis possible tocalculate the wavelength(lamda)usingthe followingformula: