1. AP Physics
Waves Pt 2

2. Mechanical vs. Electromagnetic
Mechanical waves: require a medium
Ex: Sound
Electromagnetic waves: no medium
Ex: light, microwaves, UV rays

3. Electromagnetic spectrum

4. Sound Waves Longitudinal waves that travel through air
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Sound Waves
Longitudinal waves that travel through air
Loudness refers to how much amplitude or energy a sound wave is carrying; measured in decibels
Pitch is the perceived frequency (proportional but not directly) as interpreted by your ear/brain

5. Producing Sound

6. How The Ear Works

7. Range of Hearing

8. Sound Interactive Simulation
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Sound Interactive Simulation
PhET – Sound Simulation
“Measure” – Speed of Sound with 𝒗= 𝒅 𝒕 𝒂𝒏𝒅 𝒗=𝝀𝒇
“Two Source Interference”
“Listen with Varying Air Pressure” – Vacuum Pump and Bell Jar

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Sound Interference
Sound waves interfere in the same way that other waves do in space.
Constructive
Destructive

10. The Doppler Effect
This apparent change in frequency of a wave due to the motion of the source (or receiver) is called the Doppler effect.
The greater the speed of the source, the greater will be the Doppler effect.
As a wave source approaches, an observer encounters waves with a higher frequency.
As the wave source moves away, an observer encounters waves with a lower frequency.

11. Doppler Effect http://www.lon-capa.org/~mmp/applist/doppler/d.htm
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Doppler Effect

12. The Doppler Effect, Big Bang Theory Style
BBT

13. Breaking the Sound Barrier

18. Uses of Doppler Effect Echolocation (Bats and Dolphins) Weather
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Uses of Doppler Effect
Echolocation (Bats and Dolphins)
Weather
Submarine
Police Radar
Expanding Universe
Hydrogen Spectrum

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Resonance Chamber
A standing wave is produced inside of a chamber or tube with a specific length
The number of nodes and antinodes determine the wavelength and frequency of the sound being produced

20. Resonance Chamber Harmonics (Open at both ends) Harmonics
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Resonance Chamber
Harmonics
(Open at both ends)
Harmonics
(Closed at One end)

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Resonance Example
Nodes are at closed ends and antinodes are at open ends
From a node to an antinode (or vice versa) is 1/4th of a wavelength.
Also…

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Resonance Example
Every half wavelength of distance will be another antinode and node
Therefore, the same frequency will resonate again.
For example…

23. Speed of Sound (Example 1 - E)
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Speed of Sound (Example 1 - E)
An “E” is a 1.04 m wavelength sound wave.
The tuning fork of an E note has a frequency of 320 Hz is stamped on it
v = fl = (320 Hz)*(1.04 m)
= 333 m/s

24. Resonance Tube