Chapter 11+12: Waves and Sound

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Chapter 11+12: Waves and Sound by Mind Map: Chapter 11+12: Waves and Sound

1. Intensity: measure of power/unit

1.1. decreases as the distance from source increases

2. Wave: disturbance that travels away from its source

2.1. Transverse (S)

2.1.1. Perpendicular

2.1.2. Ex: Seismic

2.2. Longitudinal (P)

2.2.1. Parallel

2.2.2. Ex: Seismic, sound

3. Periodic Wave

3.1. Frequency: Occurence of pattern repeating

3.1.1. Inverse of period

3.2. Repeats the same pattern

3.3. Period: time is takes for one wave

3.4. Amplitude: height of wave

3.5. Wavelength:distance of wave travel

4. Additional Wave Properties

4.1. Reflection of waves: ave with an abrupt boundary between mediums

4.2. Refraction: Change in propagation direction

4.3. Compression: waves are bunched

4.4. Rarefaction: Waves are spread

5. Multiple Waves

5.1. Interference

5.1.1. Destructive: waves 180 degrees out of phase

5.1.2. Constructive: waves in phase of eachother

5.2. Incoherent: phase relationship varies randomly

5.3. Coherent: same frequency and fixed phase

6. Main Properties:

6.1. mass density increases=decrease in speed

6.2. Increase in tension=increase in speed

7. Standing Wave

7.1. One wave is reflected and interferes with incident wave

7.2. Anti-Node: halfway in between nodes

7.3. Node:Halfway between points of max. amplitude

7.4. Fundamental Frequency: lowest freq. standing wave

8. Sound Wave

8.1. Uniform distribution of molecules is disturbed

9. Frequencies of sound wave

9.1. Audible range: 20Hz-20kHz

9.2. Infrasound: below 20Hz

9.3. Ultrasound: abover 20kHz

9.4. audible range varies with animals

10. Speed of sound wave

10.1. Square root of Frequency/linear mass density

10.2. Increases .606m/s per each degree C increase

10.3. Speed of sound at room temp (293K): 343 m/s

10.4. Intertia: characterized by mas density

10.5. Speed of sound at 273K: 331 m/s

11. Amplitude + Intensity of Sound wave

11.1. Pressure Amplitude

11.1.1. Pressure fluctuation above/below pressure in absense of wave

11.2. Displacement Amplitude

11.2.1. mas. displacement of an element of medium from equilibrium

11.3. Intensity is proportional to amplitude squared

11.4. Threshold of hearing:reference intensity with intensity level

11.4.1. 1E-12 W/m2

11.5. Intensity increase of a factor of 10; 10dB added

11.6. Intensity Unit: decibels

12. Standing sound waves

12.1. Pipe closed at one end

12.1.1. Wavelength: 4L/n

12.1.2. Closed end: pressure antinode + displacement node

12.2. Pipe open at both ends

12.2.1. Same boundary condition at each end

12.2.2. Wavelength:2L/n

12.2.3. Open ends: pressure nodes + displacement antinodes

13. Timbre/Tone Quality

13.1. Harmonics:fundamental and overtones

13.2. Overtone: frequencies that are not the fundamental