Phys 1 Student Workbook.pdf

Name _____________________ Class ______________ Date _________Activity P28: Interference of Sound Waves - Beats(Voltage Sensor)Concept DataStudio ScienceWorkshop (Mac) ScienceWorkshop (Win)Waves P28 Beats.DS P33 Interference-Beats P33_BEAT.SWSEquipment NeededQtyVoltage Sensor (CI-6503) 1Dual Function Generator (WA-9301A) 1Speaker (WA-9303) 1What Do You Think?In a typical classroom of science students, one or two people may play a guitar. They coulddescribe to you the phenomenon they are trying to eliminate in the process of tuning. Ask aguitar player to describe what they are listening to as they tune a guitar. Write a brief descriptionof what you hear when two slightly out-of-tune guitar strings are played at the same time.Take time to answer the ‘What Do You Think?’ question(s) in the Lab Report section.This activity examines the relationship between the beat frequency andthe frequencies of the two interfering sound waves and shows beats ona Scope display.BackgroundWhen two sound waves of slightly different frequency are producedsimultaneously, they interfere with each other and the resulting soundthat you hear is the superposition of the two waves. The combinedsound seems to be one frequency, but the intensity varies. This loudnessvariation is called beats.The beat frequency (number of beats per second) should equal thedifference between the frequencies of the waves that interfere:f beat= |f 2– f 1|SAFETY REMINDER• Follow all safety instructions.For You To DoIn this activity, use a special dual function generator to produce two sound waves of slightlydifferent frequencies. Use the Voltage Sensor to measure the combined waveform. UseDataStudio or ScienceWorkshop to display and analyze the waveform.Use one of the built-in analysis tools of the software to determine the beat frequency. Then usethe Frequency Spectrum (FFT) display to observe the dominant frequencies of each individualwave. Then compare the beat frequency to the difference in frequency of the two interferingwaves.P28 ©1999 PASCO scientific p. 201