1. Waves

2. Waves Wave: a disturbance that transfers energy from place to place.
Medium: the material through which the wave can pass.
Waves are classified by:
1. the way they move.
2. the medium through which the wave can pass.

3. Transverse waves: Particles of the medium move
perpendicular to the direction of wave motion.
(looks like a jump rope)
2. Can travel through liquids, gases, empty space and SOME solids.
Ex) Ocean waves

4. Longitudinal Waves Particles of the medium move parallel
to the direction of wave motion.(looks like a slinky)
Ex) sound and water

5. Wave Components

6. Crest
Crest - maximum positive distance from the rest position, top of the wave
Peak

7. Trough
Crest - maximum positive distance from the rest position, bottom of the wave
Valley

8. Amplitude
Amplitude - the height of the wave, either rest position to crest or rest position to trough
Amplitude is 1/2 the total displacement
Tells the strength, power, intensity of a wave
Ex: sound - volume, light - brightness, earthquakes - power
Units = Meters

9. Wavelength
Wavelength - the distance from one corresponding point on a wave to the same point on the next wave
Crest to crest, or trough to trough
Units are Meters

10. Frequency
Frequency - the number of waves that pass a fixed point in a given amount of time
Greater frequency, greater the energy
Units are waves per second, Hertz (Hz)

11. Velocity
Velocity - the speed and direction of the wave, distance divided by time
Units are m/s
The velocity of a wave changes in every new medium it enters
Medium - the material a wave is traveling through
Sound travels at ~343 m/s and light at ~300,000,000 m/s

12. Velocity = frequency x wavelength
Wave Formula
Wave formula
v = f x w
Velocity = frequency x wavelength
Ex: A wave traveling at 3.0x108 m/s has a frequency of 10,000Hz. What is the wavelength of the wave?
3.0x108 m/s = 10,000Hz x w
w = 3.0x108 m/s / 10,000Hz = 30,000m

13. Reflection
Reflection - waves strike a surface they reflect and invert.
Ex: Sonar - sound, radar - radio waves, echoes for sound, satellites

14. Part 2 - Reflection Reflection from a mirror: Mirror Normal
Incident ray
Reflected ray
Angle of incidence
Angle of reflection
Mirror

15. Only red light is reflected
Seeing color
The color an object appears depends on the colors of light it reflects.
For example, a red book only reflects red light:
Homework
White
light
Only red light is reflected

16. A white hat would reflect all seven colours:
A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):
Purple light
A white hat would reflect all seven colours:
White
light

17. A white hat would reflect all seven colours:
A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):
Purple light
A white hat would reflect all seven colours:
White
light

18. In different colours of light this kit would look different:
Red
light
Shirt looks red
Shorts look black
Shirt looks black
Blue
light
Shorts look blue

19. Refraction
Refraction - waves bend when entering a new medium, the change in density causes the wave to change speed
Ex: Pencil bends in water, fish look bigger in water

22. Diffraction Diffraction - waves bend around an obstacle in their path
Ex: sound can bend around corners, light can fan out through small openings

23. Interference
Interference - two or more waves traveling in the same medium can interact. They can reinforce each other called constructive interference (in-phase) or oppose each other called destructive interference (out-of-phase)
Ex: Waves can add or subtract to form a new wave (Rogue wave in ocean)

24. The Doppler Effect
Doppler Effect - change in frequency of a wave based on the motion of the source or observer
the frequency of a wave appears higher when approaching and lower when moving away from the observer
Works for all waves

25. Doppler Effect - Sound
Sounds appear higher in frequency (pitch) when approaching and lower when moving away
Ex #1 - An police siren sounds higher frequency (pitch) when approaching and lower when moving away

26. Doppler Effect - Light
Light appears higher in frequency (closer to purple) when approaching and lower (closer to red) when moving away
Ex #2 - Light appears higher frequency when approaching (Blue-Shift) and lower frequency when moving away (Red-Shift). Hubble proved the universe is expanding because light is shifted towards the red frequencies.

27. Sound
Sound - mechanical wave caused by objects vibrating, which compresses and expands air molecules
Speed of sound increases with temperature

28. Sound - Compressional
Compressional (longitudinal) wave, moves faster through dense objects, can’t go through a vacuum

29. The Ear

31. The Electromagnetic Spectrum
Electromagnetic waves - energy caused by vibrating charged particles such as electrons
All move the speed of light = 3.0 x 108m/s
Can travel through nothing at all (vacuum), and go faster through less dense mediums
Are ordered based on energy, frequency, and wavelength
Order: radio, microwaves, infrared (heat), visible light, ultraviolet, x-rays, and gamma
ROYGBIV are the colors of visible light

32. Electromagnetic continued…
Energy of electromagnetic waves are electron volts (eV)
We only see the colors of visible light, but many of the other waves can be detected with special instruments, some animals don’t see with visible light (insects, reptiles)
Overexposure to the waves higher in energy than visible light (UV, x-ray, and gamma) can be harmful causing cancer and genetic mutations
Electromagnetic energy is often aborbed into heat

33. Daily Quiz Questions #1-5 labels the parts of the wave on the board
6. What is it called when a wave bends in a new medium?
7. What is it called when a wave bounces off a surface?
8. What is it called when a wave bends around an obstacle?

34. Daily Quiz
9. What part of the wave tells you the intensity of the wave?
10. What is the length of the wave called?
11. What is the number of waves per second called?
12. What are the units for wavelength?
13. What are the units for frequency?

35. Daily Quiz
14. Which type of wave vibrates parallel to the direction it travels?
15. Which type of wave vibrates perpendicular to the way it travels?
16. True or False. Sound is produced by vibrating objects.
17. True or False. Sound can travel through a vacuum.
Bonus #1 - What is the change in frequency called when an object approaches and leaves/
Bonus #2 - What does Mach 2 mean (Think sound)?