1. Properties of Waves
Waves have energy and transfer energy when they interact with matter
They cannot travel through empty space!

2. Types of Waves
Transverse and Longitudinal

3. Transverse Wave: perpendicular disturbance

4. Longitudinal Wave: parallel disturbance

5. Compression and Rarefaction
Compression Rarefaction

6. Distance between the crest of one wave and the crest of the next wave
Wavelength
Distance between the crest of one wave and the crest of the next wave

7. Increases with increasing energy
Amplitude
The height of a wave
Increases with increasing energy

8. Frequency
The number of oscillations per second
Units of Hertz

9. Period: time it takes for one complete wave to pass a given point
measured in seconds
depends on the medium in which the waves are traveling

10. Period and Frequency Are The Inverse of Each Other
Frequency = 1/Period
Period= 1/Frequency
Gusts of wind cause the Sears Building in Chicago to sway back and forth, completing a cycle every ten seconds.
What is its frequency? 1/10Hz
What is its period? 10s
An electric toothbrush completes 90 cycles every second.
What is its frequency? 1/90 hz
What is its period? 1s

11. Wave Motion: Transporting Energy
When you talk the energy from your voice travels across the room at about 340 m/s. Wave energy travels through the air. The air itself does not travel at this speed. If it did think how windy it would be!

12. Wave Speed= Frequency x Wavelength
If a train of freight cars, each 10m long, rolls by your at a rate of three cars per second, what is the speed of the train? 30 m/s
If a water save vibrates up and down three times each second and the distance between the crests is 2m.
What is the frequency? 3 Hz
What is the wavelength? 2m
What is the speed? 6 m/s

13. Pitch How high or low a sound is perceived by the human ear.
Higher Frequency = Higher Pitch

14. Reflection
The bouncing back of waves

15. Reflection of Sound
An Echo

16. Regular Reflection
The angle of incidence and angle of reflection are equal

17. Irregular or Diffuse Reflection
Also known as “scattering.”

18. Refraction:
The bending of a wave due to a change in medium

19. Refraction of Light

20. Refraction of Sound
During the day the air near the ground is generally warmer than the air above. So the speed of sound near the ground increases. This causes them to bend away from the ground resulting in a sound that doesn’t seem to carry well

21. Resonance: sounding again
When the frequency of vibrations of one object matches the frequency of another.
In order for something to resonate, it needs a force to pull it back to its starting position and enough energy to keep it vibrating.

22. the ability of two or more waves to reinforce or cancel each other
Interference
the ability of two or more waves to reinforce or cancel each other

23. Resonance and Beats
Two identical tuning forks and sounding boxes are placed next to one another. Striking one tuning fork will cause the other to resonate at the same frequency. When a weight is attached to one tuning fork, they are no longer identical. Thus, one will not cause the other to resonate. When two different tuning forks are struck at the same time, the interference of their pitches produces beats.

24. Diffraction
When waves bend or spread out around an obstacle.

25. Properties of Sound
Sound waves are transverse waves

26. The Doppler Effect and Sound
As a sound source mores toward the listener the waves reach the listener with a higher frequency causing the pitch to appear to increase.
The opposite occurs as it moves away

27. The Doppler Effect and Light
When a light source moves away this is called a red shift.
The is due to the decrease towards the red end of the color spectrum.
When a light source approaches this is called a blue shift.
This is due to the increase toward the high frequency blue end of the color spectrum.

28. Galaxies appear to be spreading away from a central point
Galaxies appear to be spreading away from a central point. Scientists are able to observe this phenomenon and calculate the speed of the galaxies by using the Doppler Effect.
What type of color shift would a scientist see from a galaxy moving away?
Red Shift

29. A Distant Star is Spinning Rapidly. Which side would show a blue shift
A Distant Star is Spinning Rapidly. Which side would show a blue shift? Which side would show a red shift?
The side turning towards us would have a blue shift
The side turning away from us would have a blue shift
This allows scientists to calculate the spin rate of distant stars.

31. Bow Waves
Waves created when an object moves faster than the waves it creates.
Similar to the wake created by a boat.

32. Shock Waves & Sonic Boom
The bow wave of a speedboat that passes by can splash you if you are at the water’s edge. In a sense you can say you were hit by a “water boom.”
In the same way, when the conical shell of air behind a supersonic aircraft reaches listeners on the ground, the sharp crack they hear is described as a “sonic boom.”

33. The Speed of Sound Elasticity Density Temperature
Depends on 3 Characteristics of the Medium:
Elasticity
Density
Temperature