1. Welcome back!!!
Starting waves today
QUIZ Weds
Test next
Friday

2. WAVES
Repeating movement or disturbance that transfers ENERGY, not stuff’’ thru matter or space.

3. Mechanical Require a MEDIUM to travel; can be solid, liquid or gas.
Examples: SOUND, earthquakes, water waves

4. DO NOT Require a MEDIUM to travel; can travel thru empty space
electromagnetic
DO NOT Require a MEDIUM to travel; can travel thru empty space
Examples: LIGHT

5. 1. mechanical Transverse (sine) Matter moves up and
Examples
Seismic
Ocean
Surface
Transverse (sine)
Matter moves up and
down while energy moves thru
Amplitude -measurement of how much energy a wave carries!
CREST
wavelength
baseline
trough
amplitude

7. 1. mechanical sound longitudinal (compressional)
Examples
sound
longitudinal
(compressional)
Energy and matter move in the
same direction
wavelength
rarefaction
compression

9. v = f The Math Period: How long it takes for 1 full wave to pass
frequency: How many waves pass per second
v = f

10. Practice 1

11. Practice 2

12. Practice 3

13. Practice 4

14. Practice Problem 5
A tuning fork has a frequency of 280 Hz. and the wavelength of the sound produced is 1.5 m. Calculate the velocity.

15. Practice Problem 6
A wave is moving toward shore with a velocity of 5.0 m/s. If its frequency is 2.5 hertz, what is its wavelength?

16. Practice Problem 7
The speed of light is 3.0 x 108 m/s. Red light has a wavelength of 7 x 10-7 m. What is its frequency?

17. Practice Problem 8
The frequency of violet light is 7.5 x 1014 hertz. What is its wavelength?

18. Practice Problem 9
A jump rope is shaken producing a wave with a wavelength of 0.5 m with the crest of the wave passing a certain point 4 times per second. What is the velocity of the wave?

19. Practice 10
Waves in a lake are 6 m apart and pass a person on a raft every 2 s. What is the frequency, period, wavelength, and speed of the waves?

20. PRACTICE 11
1. How many full wavelengths are there in this wave?            
2. Measure one Wavelength: ______ cm           
3. Measure the Amplitude: _______ cm        
4. If this picture was taken over one second, what is the frequency of the wave? ________ Hz   
5. You measured the wavelength and found the frequency of the wave. Use these two measurements to calculate the speed of the wave in centimeters per second (cm/s):

21. Practice 12

25. Behavior of waves
Reflection

26. Behavior of waves
Refraction

27. Behavior of waves
Diffraction

29. WAVE INTERFERENCE

30. CONSTRUCTIVE

31. DESTRUCTIVE

32. Practice 13

35. STANDING WAVES

36. STANDING WAVES

38. Practice 14
The string at the right is 6.0 meters long and is vibrating as the third harmonic. The string vibrates up and down with 45 cycles in 10.0 seconds. Determine the frequency, period, wavelength and speed for this wave.

39. Practice 14
Waves in a lake are 6 m apart and pass a person on a raft every 2 s. What is the frequency, period, wavelength, and speed of the waves?

40. PHET Wave on a String
file:///C:/Users/Looper/AppData/Local/Temp/wave-on-a-string_en.html

41. RESONANCE
Gallopin Gertie
Physics Girl
glasses

42. MORE ON SOUND
sonic boom
Musical Highways
Sound Waves

43. THE DOPPLER EFFECT
Big Bang Theory

44. YOUR TURN #2
A buoy bobs up and down in the ocean. The waves have a wavelength of 2.5 m, and they pass the buoy at a speed of 4.0 m/s. What is the frequency of the waves? How much time does it take for one wave to pass under the buoy?

45. EM WAVES

46. EM WAVES

47. EM WAVES

48. Ripple tanks
ripple tanks

49. polarization

50. 25.2 Wave Description think!
What is the frequency in vibrations per second of a 100-Hz wave?

51. 25.2 Wave Description think!
What is the frequency in vibrations per second of a 100-Hz wave?
Answer:
A 100-Hz wave vibrates 100 times/s.

52. 25.3 Wave Motion
think!
The Sears Tower in Chicago sways back and forth at a frequency of about 0.1 Hz. What is its period of vibration?

53. 25.3 Wave Motion
think!
The Sears Tower in Chicago sways back and forth at a frequency of about 0.1 Hz. What is its period of vibration?
Answer: The period is

54. CONCEPTS you need to know…
A surfer who wishes to ride a big wave is most interested in the ____ of a wave.
A sound wave that has a higher frequency has a wavelength that is SHORTER/LONGER?
The frequency of the second hand on a clock is
_________.
A weight on the end of a spring bobs up and down one complete cycle every 5 seconds. Its period is ________________.

55. A repeating back-and-forth motion about an equilibrium position is a vibration.
WAVE: A disturbance that is transmitted progressively from one place to the next with no actual transport of matter . TRANSFER ENERGY
Light and sound are both forms of energy that move through space as waves.

56. 25.2 Wave Description
The source of all waves is something that vibrates.

57. 25.2 Wave Description The high points on a wave are called crests.
The low points on a wave are called troughs.
The term amplitude refers to the distance from the midpoint to the crest (or trough) of the wave.
The amplitude is the maximum displacement from equilibrium.
The wavelength of a wave is the distance from the top of one crest to the top of the next one.

58. 25.2 Wave Description Frequency
The number of vibrations an object makes in a unit of time is an object’s frequency.
The frequency specifies the number of back-and-forth vibrations in a given time (usually one second).
The unit of frequency is called the hertz (Hz).
A frequency of one cycle per second is 1 hertz, two cycles per second is 2 hertz, and so on.

59. 25.2 Wave Description
If you know an objects frequency you can calculate it’s PERIOD. The time it takes to do complete cycle.
What is the period of a wave that has a wavelength of 0.80 m and is traveling at 2.0 m/s?

60. Wave Parts Definitions
Amplitude—the height of a wave from equilibrium to crest (or trough)
Period—the time it takes for one entire wave to pass a point
Frequency—the number of waves that pass a given point per time period

61. 25.4 Wave Speed
The speed of a wave depends on the medium through which the wave moves.
Whatever the medium, the speed, wavelength, and frequency of the wave are related.

62. Wavelengths must be measured from crest to crest.
25.4 Wave Speed
If the wavelength is 1 meter, and one wavelength per second passes the pole, then the speed of the wave is 1 m/s.
Wavelengths must be measured from crest to crest.

63. 25.4 Wave Speed
If the wavelength is 3 meters and if two crests pass a stationary point each second, then 3 meters × 2 waves pass by in 1 second.
The waves therefore move at 6 meters per second.
v = f
where v is wave speed,  is wavelength, and f is wave frequency.

64. 25.4 Wave Speed
In air, the product of wavelength and frequency is the same for every frequency of sound.
Long wavelengths have low frequencies, and short wavelengths have high frequencies.

65. 3 Types of Wave Motion Longitudinal and Transverse WaveMotion
Compressional (Longitudinal)

66. 25.5 Types of Waves
Suppose you create a wave along a rope by shaking the free end up and down.
The motion of the rope is at right angles to the direction in which the wave is moving.
Whenever the motion of the medium is at right angles to the direction in which a wave travels, the wave is a transverse wave.

67. 25.6 Longitudinal Waves
Sometimes the particles of the medium move back and forth in the same direction in which the wave travels.
When the particles oscillate parallel to or along the direction of the wave, the wave is a longitudinal wave.

68. 25.6 Longitudinal Waves
Both transverse and longitudinal waves can be demonstrated with a loosely coiled spring.
When the end of a coiled spring is shaken up and down, a transverse wave is produced.
When it is shaken in and out, a longitudinal wave is produced.

69. Medium
When a wave travels through a medium, it does not permanently displace it.
For example, when the waves in the ocean pass, the water returns to its original position.