1. Chapter 10
Waves

2. Chapter 1o Section 1
The Nature of Waves

3. What is a wave?
Wave – a repeating disturbance or movement that transfers energy through matter or space

4. What is a wave?
Wave – a repeating disturbance or movement that transfers energy through matter or space
Molecules pass energy on to neighboring molecules

5. What is a wave?
Wave – a repeating disturbance or movement that transfers energy through matter or space
Molecules pass energy on to neighboring molecules
Waves carry energy not matter.

6. What is a wave?
Wave – a repeating disturbance or movement that transfers energy through matter or space
Molecules pass energy on to neighboring molecules
Waves carry energy not matter.
All waves are produced by something that vibrates. (anything that moves up and down or back and forth)

7. A Medium A medium is a material through which a wave travels.
can be solid, liquid, or gas
not all waves need a medium to travel through
Example – Light waves or Radio Waves

8. Mechanical Waves
A mechanical wave is a wave that can travel only through matter. (solid, liquid, gas)
Example: Sound wave
Question: Is there sound in space?

9. Is their sound in space?

10. Mechanical Waves
A mechanical wave is a wave that can travel only through matter. (solid, liquid, gas)
Transverse waves vs. Compressional waves

11. Transverse waves
Matter in a medium moves back and forth at right angles to the direction that the wave travels.
AKA an S-Wave
Ex. Water waves

12. Compressional Waves
Matter in the medium moves in the same direction that the wave travels.
AKA P-waves
Ex. Sound waves

13. Combination of Waves
Some waves are not purely transverse or compressional but instead will have a combination of both types of waves.
Ex. Seismic waves

14. http://video. nationalgeographic

15. Wave Properties
Chapter 10 Section 2

16. Waves can differ in… How much energy they carry How fast they travel
How they look

17. Parts of a Wave Transverse waves Crests – the high points
Troughs – the lowest points

18. Parts of a Wave Compression waves compressions – the dense regions
rarefactions – the less dense regions

19. What is Wavelength?
The distance between one point in the wave and the nearest point just like it.

20. Frequency…
Frequency is how many wavelengths pass a fixed point each second
# expressed in hertz (Hz)
As frequency increases, wavelength decreases
The frequency of a wave equals the rate of vibration of the source that creates it.

21. Frequency
A period of a wave is the amount of time it takes one wavelength to pass a point.
As the frequency of a wave increases, the period decreases.
Period has units of seconds.

22. Wave Speed
Wave velocity, or v, describes how fast the wave moves forward.
Velocity = wavelength x frequency or v = λ x f
light waves travel faster than sound waves (ex. thunder and lightning, baseball bat)
Sound waves travel faster in liquids and solids than in gas.
Light waves travel faster in gases and empty space than in liquids and solids.

23. Amplitude Amplitude is the measure of the energy in a wave.
Amplitude of a compressional wave is related to how tightly the medium is pushed together at the compression
the denser the compressions, the larger the amplitude is and the more energy the wave carries
the less dense the rarefactions, the larger the amplitude and the more energy the wave carries

25. The Behavior of Waves
Chapter 10 Section 3

26. Reflection
Reflection occurs when a wave strikes an object and bounces off of it.

27. Reflection
Reflection occurs when a wave strikes an object and bounces off of it.
All types of waves can be reflected
The angle of incidence of a wave is always equal to the angle of reflection.

28. Reflection
Reflection occurs when a wave strikes an object and bounces off of it.
All types of waves can be reflected
The angle of incidence of a wave is always equal to the angle of reflection.
Normal – an imaginary line perpendicular to a reflective surface
Angle of incidence – the angle formed by the wave striking the surface and the normal
Angle of reflection – the angle formed by the reflected wave and the normal

29. Refraction
Refraction – the bending of a wave caused by a change in its speed as it moves from one medium to another

30. Refraction
Refraction – the bending of a wave caused by a change in its speed as it moves from one medium to another
The greater the change in speed is, the more the wave bends
When a wave passes into a material that slows it down, the wave is bent toward the normal
When a wave passes into a material that speeds it up, the wave is bent away from the normal.

31. Normal

32. Diffraction – an object causes a wave to change direction and bend around it

33. Diffraction – an object causes a wave to change direction and bend around it

34. Diffraction
Diffraction – an object causes a wave to change direction and bend around it
If the object is smaller than the wavelength, the wave diffracts a lot.
If the obstacle is much larger than the wavelength, the wave does not diffract much
The larger the obstacle is compared to the wavelength, the less the waves will diffract.

36. Diffraction and Radio Waves
AM radio waves have longer wavelengths than FM radio waves.
Because of these longer wavelengths, AM radio waves diffract around obstacles like buildings and mountains.
AM radio reception is often better than FM reception around these large structures.

37. Interference
The ability of two or more waves to combine and form a new wave.

38. Interference
The ability of two or more waves to combine and form a new wave.
Waves pass right through each other and continue in their original direction.

39. Interference
The ability of two or more waves to combine and form a new wave.
Waves pass right through each other and continue in their original direction.
New wave exists only while the two original waves continue to overlap

40. Interference
The ability of two or more waves to combine and form a new wave.
Waves pass right through each other and continue in their original direction.
New wave exists only while the two original waves continue to overlap
Constructive interference – waves add together
Destructive interference – waves subtract from each other

42. Standing Waves
Standing waves – a wave pattern that stays in one place

43. Standing Waves Standing waves – a wave pattern that stays in one place
Form when waves of equal wavelength and amplitude that are traveling in opposite directions continuously interfere with each other.
Nodes form at the places where two waves always cancel each other.

45. Resonance
Resonance – the ability of an object to vibrate by absorbing energy at its natural frequency.