1. Waves
Physical Science

2. What is a Wave?
Movement of energy through a medium by vibrations

3. Mediums are what? Materials that waves transfer though Types Liquids
Air/gases
Solid best for sound waves

4. What moves in a Wave? Energy
A wave will move as along as it has energy to carry

5. Types of Waves Mechanical Waves Surface Waves
Is a disturbance in matter that carries energy from one place to another
Ex: sound waves
Surface Waves
Is a wave that travels along a surface separating two mediums
Ex: ocean waves (water and air)

6. Types of Waves Electromagnetic Waves
Transverse waves consisting of changing electric fields & changing magnetic fields
Ex: x-rays, radio waves

7. Types of Mechanical Waves
Transverse Waves
Is a wave that causes a medium to vibrate at right angles to the direction of travel
Up and Down motion
Ex: Light waves

8. Wave Parts—Transverse Waves only
Crest—highest point on a wave (top of wave)
Trough—lowest point on a wave (bottom of wave)

9. Types of Mechanical Waves
Longitudinal Waves
Is a wave in which the vibration of the medium is parallel to the direction of travel.
Back and forth motion
AKA: compressional waves
Ex: Sound Waves

10. Wave Parts—Longitudinal Waves Only
Compression—area where particles are close together
Rarefaction—area where particles are spread out

11. Wave Parts Transverse & Longitudinal Waves
Wavelength
Distance between a point on one wave to the same point on the next wave
Transverse Waves
Crest to crest
Trough to trough
Longitudinal Waves
Compression to compression

12. Wave Parts Transverse & Longitudinal Waves
Amplitude
Max displacement of the medium from resting position
Transverse Wave
Resting position to crest/trough
Longitudinal Wave
How compressed the compressions are

13. Transverse Wave Diagram
Crest
Trough
Wavelength
Amplitude
Wave Height
Resting Position

14. Longitudinal Wave Diagram
Compression
Rarefaction
Wavelength

15. Frequency of a Wave
Amount of waves that pass a given point in one second
Unit= Hertz (Hz)
Transverse waves
Count the top and bottom pairs
Longitudinal waves
Count the compressions

16. Frequency Practice

18. Frequency & Energy Relationship
As frequency increases, the energy in a wave increases
They do the same

19. Frequency & Wavelength Relationship
Increase frequency decrease the wavelength of a wave
They do the opposite

20. Wavelength & Energy Relationship
Increase the wavelength will decrease the energy
They do the opposite

21. Amplitude & Energy Relationship
As the energy of a wave increases, the amplitude increase

22. Frequency & Period Relationship
What is Period?
The amount of time it takes one wavelength to pass a point
Relationship
As the frequency of a wave increase, the period decreases.

23. Wave Speed = frequency * wavelength
Wave Speed Formula
Wave Speed = frequency * wavelength
Vw = f * λ
Vw= wavespeed (m/s)
f = frequency (Hz)
λ = wavelength (m)

24. Wave Speed Example Problems
A wave has a wavelength of 4 meters and a frequency of 20 Hz. What is the speed of the wave?
A wave has a speed of 10 m/s and a length between the crests of 0.5 meters. What is the frequency of the wave?

25. Speed of Light and Sound
Light Waves = 3 x 108 m/s
Sound waves = 340 m/s
Light travels faster than sound
This is why you see lighting before hearing thunder

27. Wave Interactions
How waves behave when they meet a surface, barrier, or another wave
Four Basic Types
Reflection
Refraction
Diffraction
Interference

28. Reflection Waves bounce off or back
Speed and Frequency does not change
Two Types
Regular
Diffuse
Ex: Sonar, Radar

29. Types of Reflections Regular Diffuse
All waves bounce off a surface at the same angle
Image is clear
Diffuse
Waves scatter off a bumpy surface
Image is hard to see

30. Refraction Bending of a wave as it enters a new medium at an angle
Direction never changes but wavelength and speed does
Ex:
waves coming inshore
pencil in cup of water
Light entering glass

31. Diffraction
Bending of a wave as it moves around an obstacle or passes through a narrow opening
Ex:
Ocean waves with a barrier
Why you hear a parade around a corner
Causes light to scatter (reason the sky is blue)

32. Interference Occurs when two waves overlap and combine together
Two Types
Constructive
Destructive

33. Constructive Interference
When two waves moving in the same direction collide and produce a wave with a larger displacement

34. Destructive Interference
When 2 waves moving in opposite directions, collide and produce a wave with a smaller displacement

36. Electromagnetic Waves
Placed in the electromagnetic spectrum
Arranged by wavelength and frequency
Can travel through a vacuum
Likes no medium

37. Electromagnetic Spectrum
AKA: E-M spectrum
Moving from left to Right
Wavelength Decrease
Frequency Increases

38. Types of Electromagnetic Waves
Radio Waves
Longest Wavelength
Lowest frequency
Types: radio, TV, microwaves, radar
Infrared Rays
Can’t see with out eyes
Used to Detect Heat
Ex: heat lamps, night vision goggles

39. Types of Electromagnetic Waves
Red Light
Longest wavelength
Lowest frequency
Violet Light
Shortest wavelength
Highest frequency
Visible Light
We Can See
White Light can be broken down
ROY G BIV

40. Types of Electromagnetic Waves
Ultraviolet Rays
Body uses to make vitamin D
Causes sunburns
Can cause skin cancer
We can’t see
X-Rays
Can pass through skin
Cannot go through bones

41. Types of Electromagnetic Waves
Gamma Rays
Highest Frequency on E-M spectrum
Highest energy on E-M spectrum
Found in Space
Stopped by 3-m of lead