1. Day 1 - Wave Characteristics
Waves and Sound
Day 1 - Wave Characteristics

2. What are waves?
Def. - Disturbances that carry energy from place to place, through matter or space.

3. Waves are made when you speak And heard when you listen
Waves can travel through space
Most waves begin with a vibration
Waves are made when you speak
And heard when you listen
Waves can make the earth move and shake
And make the light you see

4. is the material in which a wave moves
gas
Liquid
A medium can be a:
Music from your radio to your ear
How dolphins communicate
solid
wood of a guitar
Medium
is the material in which a wave moves

5. The medium can move in two ways:
Motion of Medium
Energy moves through the medium. The medium just vibrates back and forth and doesn’t move with the wave.
The medium can move in two ways:
1. Transverse waves
2. Longitudinal waves

6. Medium moves at right angles to the direction of the wave.
Transverse waves
Medium moves at right angles to the direction of the wave.
Ex) football stadium wave
A) Crest: highest point
B) Trough: lowest point

7. Rest position or Parts of a Transverse Wave Crest Amplitude Trough
Wavelength
Amplitude
Rest position or
Trough

8. A) Compressions: where the molecules are crowded together
Longitudinal waves
Medium moves parallel to the direction of the wave Ex. – a “slinky” or metal spring
Made up of:
A) Compressions: where the molecules are crowded together
B) Rarefactions: where the molecules spread apart.

9. Compression Compression Rarefaction Parts of a Longitudinal wave
Wavelength:
Compression
Compression + Rarefaction
Compression
Rarefaction

10. Wave characteristics
Wavelength: the distance between a point on one wave and the identical point on the next. (crest to crest, compression to compression)
Unit: meter
Symbol: l Lambda

11. Directly related to the amount of energy carried.
Amplitude
Def: the distance from the crest or trough of a wave to the rest position.
Directly related to the amount of energy carried.

12. If 3 waves went by in 1 second… You have 3 waves per Second
Frequency: the # of waves that pass one place each second.
Unit: hertz (Hz)
If 3 waves went by in 1 second…
You have 3 waves per Second
Frequency would be 3 Hz

13. Waves and Sound
Day 2 -
Calculating Speed
of a
Wave

14. The Speed of a Wave is affected by two things...
1.) Type of Medium
2.)Temperature

15. Why?

16. Waves travel fastest in solids, slowest in gases.
Type of medium
Solid
Liquid
Gas 3
Waves travel fastest in solids, slowest in gases.

17. Do molecules move faster or slower as temperature increases?
So would sound travel faster or slower as temperature increases?

18. Air = 340 m/s water= 1440 m/s steel = 5000 m/s
Speed of sound
Sound waves travel slower than light waves
Speed varies, depending on the medium
Air = 340 m/s
water= 1440 m/s
steel = 5000 m/s

19. V= l x f Velocity (m/s) Frequency (Hz) Greek ‘lambda’
Wave speed Equation
Velocity (m/s)
Frequency (Hz)
V= l x f
Greek ‘lambda’
Stands for wavelength (m)

20. Sample wave problems...
A tuning fork has a frequency of 280 Hz and the wavelength of the sound produced is 1.5 meters. Calculate the velocity of the wave.
Step 1
Step 2
Step 3
Step 4

21. Sample wave problems...
A wave is moving toward shore with a velocity of 5 m/s. If its frequency is 2.5 Hz, what is its wavelength?
Step 1
Step 2
Step 3
Step 4

22. Sample wave problems...
Earthquakes can produce three types of waves. A typical “S” wave travels 5000m/s. Its wavelength is about 417m. What is the frequency?
Step 1
Step 2
Step 3
Step 4

23. Waves and Sound
Day 3 - Wave Behaviors

24. Wave Behaviors Interference 3. Refraction Reflection 4. Diffraction
Four types
Interference 3. Refraction
Reflection 4. Diffraction

25. Reflection
Bouncing back of a wave after it strikes a barrier that does not absorb the energy.
An echo is a
Sound wave
that has been
reflected
Barrier

26. Angle of incidence = angle of reflection
Law of Reflection
Angle of incidence = angle of reflection

27. Used to locate underwater objects and distances.
sonar
Used to locate underwater objects and distances.
***Reflection**

28. Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb
Regular sonogram 3D sonogram

29. Refraction: Bending of waves due to a change in speed (this occurs because the wave changes mediums)

31. Refraction Why does the pencil appear to be broken when placed in a beaker of water??

32. Diffraction: Bending of waves around the edge of a barrier

33. There are two types of Wave interference: 1. Constructive Interference
Def. - Interference is the result of two or more waves passing through a medium at the same time.
There are two types of Wave interference:
1. Constructive Interference
2. Destructive Interference

34. Wave interference
Constructive Interference: two crests meet and make a wave with a bigger amplitude.

35. Wave interference
Destructive Interference: one crest & one trough meet and make a wave with a smaller amplitude..

36. Waves and Sound
Day 4 -
Intro to Sound

37. Def. – the study of the science of sound
Acoustics
Def. – the study of the science of sound
Knowledge of acoustics is important to people who design libraries, concert halls, auditoriums, etc.

38. (cannot travel in a vacuum)
Sound
Longitudinal Wave
an oscilloscope is used to convert sound waves into transverse waves, so that we can study them
Requires a medium
(cannot travel in a vacuum)

39. High frequency = High pitch
The highness or lowness of sound.
Depends on the frequency of sound waves.
High frequency = High pitch
Low frequency = Low pitch

40. Ultrasonic Sound: above 20,000Hz
Human Ear 20Hz Hz
Infrasonic: below 20 Hz
Ultrasonic Sound: above 20,000Hz

41. Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb
Regular sonogram D sonogram

42. Supersonic: faster than the speed of sound.
Transonic: where only some parts of the air around an object (such as the ends of rotor blades) reach supersonic speeds (typically somewhere between Mach 0.8 and Mach 1.2).
A US Navy F/A-18E/F Super Hornet in Transonic Flight

43. An equal mixture of all frequencies of sound
White Noise
An equal mixture of all frequencies of sound

44. Change in pitch due to motion.
Doppler
effect
Change in pitch due to motion.

45. *moving towards increases the pitch *moving away decreases the pitch
Doppler
effect
*moving towards increases the pitch
*moving away decreases the pitch
zoom
New word for the day: Dopeler Effect (n) The tendency of stupid ideas to seem smarter when they come at you rapidly.

46. Large Amplitude = Loud sound Small Amplitude = Soft sound
Intensity
Amount of energy
measured in decibels (dB)
Depends on the amplitude of sound waves.
Large Amplitude = Loud sound
Small Amplitude = Soft sound

47. Measurement of loudness
Decibels
Near total silence - 0 dB
A whisper - 15 dB
Normal conversation - 60 dB
Lawnmower - 90 dB
Threshold of pain dB
A rock concert or a jet engine dB
Gunshot, firecracker dB

48. A sound tube designed to decrease roadway noise
Noise Pollution
Displeasing sounds that disrupt the activity or happiness of human or animal life.
Causes:
Damage to the ear
Stress
Hearing Loss
A sound tube designed to decrease roadway noise