+ Perceiving Sound. + Before we start! A review of Light.
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Transcript of + Perceiving Sound. + Before we start! A review of Light.
![Page 1: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/1.jpg)
+
Perceiving Sound
![Page 2: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/2.jpg)
+Before we start! A review of Light
![Page 3: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/3.jpg)
+Light vs. Sound
Light Sound - Transverse waves -Longitudinal waves Electromagnetic waves
- mechanical waves: require a medium to travel.
![Page 4: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/4.jpg)
+What do you think is going to happen?
Make a prediction.
What will happen when air is removed from the bell jar?
Don’t forget to explain why.
![Page 5: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/5.jpg)
+Make Observations
![Page 6: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/6.jpg)
+Why did this happen?
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+Sound is…
A mechanical wave.
Longitudinal wave.
Produced by the vibration of an object and transmitted to the object’s environment.
Requires a medium.
![Page 8: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/8.jpg)
+The speed of Sound
It changes from one medium to another.
![Page 9: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/9.jpg)
+Why is that?
Using the particle model to justify your answer. Why does sound travel faster in solids than in gases?
![Page 10: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/10.jpg)
+The Decibel (Db)
The unit of measurement for the intensity of sound.
High Intensity sound = High amplitude = More Decibels.
Low Intensity sound = Low amplitude = Low Decibels.
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+
![Page 12: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/12.jpg)
+The Decibel Scale
All decibel measurements are not completely accurate, they are related to our perception by the human ear.
A sound measuring 0 Db is can barely be heard by the ear.
We measure variations on the scale by a factor of 10.
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+A Sample of a Decibel Scale
Another one can be found on p. 103 of your textbook.
![Page 14: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/14.jpg)
+Try some Questions
P. 118 # 8- 10
![Page 15: + Perceiving Sound. + Before we start! A review of Light.](https://reader031.fdocuments.in/reader031/viewer/2022032015/56649d935503460f94a79a34/html5/thumbnails/15.jpg)
+Pitch and Frequency Lower Pitch = lower frequency sound.
High Pitch = Higher frequency sound.
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+Infrasound and Ultrasounds
Infrasounds = sounds under 20Hz Used by some animals to communicate. E.g. Elephants
Ultrasounds = sounds above 20 000 Hz Used in medical imaging Used by some animals like bats (echolocation)
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+Can we hear all frequencies?
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+What happens when you age?
http://www.youtube.com/watch?v=qNf9nzvnd1k
http://www.youtube.com/watch?v=VxcbppCX6Rk