1. How many types of waves can you name?
Chapter 16
Waves and Sound
How many types of waves can you name?

2. A wave is a traveling disturbance.
16.1 The Nature of Waves
A wave is a traveling disturbance.
A wave carries energy from place to place.

3. Types of Waves (by medium)
Electromagnetic
Mechanical
Creates disturbances in electric and magnetic fields
Can travel through empty space
ex light, x rays, UV
Vibrates molecules
Needs a medium to travel (propagate)
Can not travel through empty space
Ex. sound
You can see the sun but you can not hear the sun!

4. Types of Waves (by direction of vibration)
Longitudinal
Transverse
Particles vibrate ┴ to wave propagation
Ex. Light
Particles vibrate ∕∕ to wave propagation
Ex sound

5. (aka compression wave)
16.1 The Nature of Waves
Longitudinal Wave
(aka compression wave)
Particles vibrate ∕∕ to wave motion

6. 16.5 The Nature of Sound Waves
LONGITUDINAL SOUND WAVES

7. 16.5 The Nature of Sound Waves
The distance between adjacent condensations is equal to the
wavelength of the sound wave.

8. 16.5 The Nature of Sound Waves
Individual air molecules are not carried along with the wave.

9. Does sound travel faster in a solid, liquid or gas?

10. The closer the molecules are, the faster the sound travels
16.6 The Speed of Sound
Sound travels through gases,
liquids, and solids at considerably
different speeds.
The closer the molecules are, the faster the sound travels

11. 16.1 The Nature of Waves
slow motion high angle wide shot of crowd doing "the wave" in Shea Stadium / Lon
Transverse Wave
Particles vibrate ┴ to wave motion.

12. over again by the source.
16.2 Periodic Waves
Periodic waves consist of cycles or patterns that are produced over and
over again by the source.
In the figures, every segment of the slinky vibrates in simple harmonic
motion, provided the end of the slinky is moved in simple harmonic
motion.

13. In the drawing, one cycle is shaded in color.
16.2 Periodic Waves
In the drawing, one cycle is shaded in color.
The amplitude A is the maximum excursion of a particle of the medium from
the particles undisturbed position.
The wavelength is the horizontal length of one cycle of the wave.
The period is the time required for one complete cycle.
The frequency is related to the period and has units of Hz, or s-1.

14. 16.5 The Nature of Sound Waves
THE PRESSURE AMPLITUDE OF A SOUND WAVE
Loudness is an attribute of
a sound that depends primarily
on the pressure amplitude
of the wave.

15. Relationship between wavelength and frequency

16. The # of cars that pass per unit of time is the frequency f
16.2 Periodic Waves
The # of cars that pass per unit of time is the frequency f

17. Example 1 The Wavelengths of Radio Waves
16.2 Periodic Waves
Example 1 The Wavelengths of Radio Waves
AM and FM radio waves are transverse waves consisting of electric and
magnetic field disturbances traveling at a speed of 3.00x108m/s. A station
broadcasts AM radio waves whose frequency is 1.230x106Hz and an FM
radio wave whose frequency is 91.9x106Hz. Find the distance between
adjacent crests in each wave.

18. 16.2 Periodic Waves AM FM

19. 16.5 The Nature of Sound Waves
THE FREQUENCY OF A SOUND WAVE
The frequency is the number of cycles
per second.
A sound with a single frequency is called
a pure tone.
The brain interprets the frequency in terms
of the subjective quality called pitch.

20. 4 Basic Wave Interactions
1- Interference
2- Diffraction
3- Reflection
4- Refraction

21. 17.1 The Principle of Linear Superposition
When two or more waves are present simultaneously at the same place,
the resultant disturbance is the sum of the disturbances from the individual
waves.
Constructive vs Destructive Interference

22. Constructive Interference
In phase (crest meets crest)
Add together to form a bigger wave
Pass through each other

23. Destructive Interference
Out of phase (crest meets trough)
Add together to form a smaller wave
Pass through each other

24. 17.2 Constructive and Destructive Interference of Sound Waves

25. Standing Wave Distance between successive nodes or antinodes is ½ λ
Nodes- points of destructive interference.
Antinodes- points of constructive interference
Standing wave vs Moving Wave

26. 17.5 Transverse Standing Waves
Transverse standing wave patters.

27. Two overlapping waves with slightly different frequencies gives rise
17.4 Beats
Two overlapping waves with slightly different frequencies gives rise
to the phenomena of beats.

28. The beat frequency is the difference between the two sound
17.4 Beats
The beat frequency is the difference between the two sound
frequencies.

29. Resonance
One vibrating object causes another object to vibrate at its natural frequency.
Ex. Pumping your legs on a swing
Shattering a glass with your voice
Myth Busters Breaking Glass With Human Voice 33.wmv

30. Reuben’s Tube
Tacoma Narrows Bridge Collapse Gallopin Gertie.wmv

31. Diffraction The bending of a wave around
an obstacle or the edges of an
opening is called diffraction.

32. Diffraction depends on the size of the wave and the size of the opening

33. 2-D Wave Simulation

34. Wave Interference - Electric Field, Interference, Diffraction - PhET

35. LAW OF REFLECTION
the angle of incidence equals the angle of reflection.
Normal- imaginary line that runs perpendicular to the surface at the point of incidence
θi = angle between the incident ray and the normal
θr = angle between the reflected ray and the normal

36. There are two types of reflection
Regular Reflection
reflection off a smooth surface
the reflected rays are parallel to each other.
A mirror image is formed
Diffuse Reflection
reflection off a rough surface
the reflected rays are scattered
No image or a distorted image is formed

37. Which is regular and which is diffuse reflection?

38. The bending of light due to a change in speed
Refraction
The bending of light due to a change in speed

39. Index of Refraction
The index of refraction of a material is the ratio of the speed of light in a vacuum to the speed of light in the material:

40. 26.1 The Index of Refraction
The slower light travels the higher the index of refraction
The index of refraction is always greater than 1

41. What is the speed of light in diamond?
v=1.24 x 108 m/s

42. What happens when light changes medium?
When light travels from a less optically dense medium to a more optically dense medium, the velocity of the wave decreases. This causes the wave fronts to bunch up and the wavelength then decreases . However, the frequency of the wave remains constant.

43. Why does light bend?

44. Why does light bend?
When the light meets the boundary at an angle, part of the wave front slows down while the other part is still moving quickly. This causes the light to bend.

46. SNELL’S LAW SNELL’S LAW OF REFRACTION
When light travels from a material with
one index of refraction to a material with
a different index of refraction, the angle
of incidence is related to the angle of
refraction by

47. A ray of light is incident on a air water boundary at an angle of 35° What is the angle of refraction?

48. Which material has the larger index of refraction
Which material has the larger index of refraction? The corn oil or the red jello?

49. Total Internal Reflection
When light passes from a medium of larger refractive index into one
of smaller refractive index, the refracted ray bends away from the
normal.
Critical angle

52. Dispersion In a dispersive media different wavelengths of light travel at different speeds therefore refract different amounts
What color is always on the top of a rainbow?
What color is always on the bottom?

53. Polarization
Why can only transverse waves be polarized?

54. The Doppler Effect The Doppler effect is the
change in frequency or pitch
of the sound detected by
an observer because the sound
source and the observer have
different velocities with respect
to the medium of sound
propagation.

55. Sonic Boom Meets Sun Dog on Vimeo
Applet: Doppler Effect