1. WAVES
Chapter 7

2. What is a wave A wave is A rhythmic disturbance
Carries ENERGY but not MATTER

3. How can a wave carry energy without carrying matter?
Even though the ball is moving from one end of the line to the other, the people are not moving with it.

4. How do waves move Mechanical Waves Move through matter
Energy moves from
particle to particle
Examples:
Water waves
Sound waves
Earthquake waves

5. How do waves move Electromagnetic Waves Move through empty space
Do not require matter or particles in order to move
Example:
Light waves

6. Compressional (or Longitudinal) Waves
Types Of Waves
Compressional (or Longitudinal) Waves
Transverse waves

7. Parts Of A Wave CREST AMPLITUDE WAVELENGTH TROUGH
high point of a transverse wave
AMPLITUDE
half the distance between the crest and trough
WAVELENGTH
TROUGH
distance from top of one crest to the top of the next OR from one trough to the next
low point of a transverse wave

8. Properties of waves
Amplitude – tells how much ENERGY the wave is carrying
Bright light has higher amplitude than dim
Loud sounds have higher amplitude than soft
Large water waves carry more energy than small ones

9. Properties of waves Red has a longer & Violet has a shorter
Wavelength (λ)–
In visible light, λ determines color λ λ
Red has a longer
& Violet has a shorter λ
Radio waves and microwaves have longer λ
X-rays and gamma ray have shorter

10. Properties of waves
Frequency – the number of λ that pass a given point in one second, measured in λ/sec = hertz
Higher frequency indicates faster vibration of whatever is generating the wave

11. Properties of waves CLICK HERE > F = < λ
Frequency and wavelength are closely related
Short λ creates a higher frequency
In sound, this causes a higher pitch
In light, violet color has a higher frequency than red
Long λ creates a lower frequency
In sound, this causes a lower pitch
In light, red color has a lower frequency than violet
CLICK
HERE
> F = < λ

12. Properties of waves WAVE SPEED Mechanical Wave
Travels faster through solids because molecules are closer together and transmit the sound better
Electromagnetic Wave
Travels faster through empty space because there are no molecules in the way to slow it down

13. When sound waves reflect from a surface, it produces an ECHO.
Wave Behavior
Reflection: a wave strikes a surface and bounces off
HELLOOOO!!!
HELLOOOO!!!
Reflection are clear when they bounce off a smooth, even surface. From a rough surface, light scatters in all directions and the reflection is distorted.
When sound waves reflect from a surface, it produces an ECHO.

14. Wave Behavior
Refraction: The bending of a wave as it moves from one medium into another because of a change in SPEED.

15. Diffraction occurs better when the barrier and λ are similar in size.
Wave Behavior
Diffraction: The bending of waves around a barrier.
LIGHT WAVES
Light waves do not diffract as much as sound waves, so you can’t see around corners.
This is because the λ of light is so much smaller than the width of a door.
Diffraction occurs better when the barrier and λ are similar in size.
SOUND WAVES
You can hear sounds from a room even when you are not in the room because the sound waves bend as they pass through the open doorway
WATER WAVES
When water waves strike obstacles such as islands, they bend around the island and keep moving. If the island was much bigger than than the wavelength of the water wave, less diffraction would occur

16. Wave Behavior
Interference: The ability of two waves to combine and form a new wave when they overlap

17. INTERFERENCE
CONSTRUCTIVE Interference

18. INTERFERENCE
CONSTRUCTIVE Interference

19. INTERFERENCE
CONSTRUCTIVE Interference

20. INTERFERENCE
DESTRUCTIVE Interference

21. INTERFERENCE
DESTRUCTIVE Interference

22. INTERFERENCE
DESTRUCTIVE Interference

23. Constructive INTERFERENCE
The crests of two waves – A & B – approach each other
The two waves form a wave with a greater amplitude while the crests of both waves overlap

24. Constructive INTERFERENCE
The original waves pass through each other and go on as they started.

25. Destructive INTERFERENCE
The crest of one wave (A) approaches the trough of another (B)
If the two waves have equal amplitude, they momentarily cancel when they meet

26. Destructive INTERFERENCE
The original waves pass through each other and go on as they started.

27. Parts of a COMPRESSIONAL WAVE:
Parts Of A Wave
Parts of a COMPRESSIONAL WAVE:
Compression
Rarefaction
Wavelength

28. What did you learn