1. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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2. Waves 2 types of waves Mechanical Electromagnetic
Use matter to transfer energy through a medium
Electromagnetic
Do not need matter to transfer energy

3. Mechanical Waves
Waves that REQUIRE a medium for the energy to travel Examples: water waves, sound waves, energy moving through a slinky. What else?

4. Mechanical Waves Use matter (Medium) to transfer energy.
The energy is transferred from particle to particle.
SOUND IS A MECHANICLE WAVE

5. There Are Two Basic Types of Mechanical Waves.
Transverse Waves
The energy traveling through the wave causes the particles to move at a right angle to the direction of the energy.
This is what we usually draw when representing waves.
Ripples on a pond are an example of these.

6. The Second type of Mechanical Wave
Compressional Waves
In this type the particles move in the same direction as the energy.
Sound is a Compressional Wave

7. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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8. Wave Properties Amplitude Wavelength Frequency
Human perception of amplitude – loudness
Human perception of frequency – pitch

9. Transverse Waves Crest – very top of wave Trough – very bottom of wave
Amplitude – Distance between resting position and crest/trough
Wavelength – Distance from the top of one crest to the next crest
Frequency – Number of wavelengths to pass by a given point in 1 second
2.5 in picture at right

10. Transverse Wave Examples

11. Transverse Waves (cont.)
Frequency and Pitch
As frequency increases pitch gets higher
As frequency decreases pitch gets lower

12. Transverse Waves (cont.)
Frequency and Wavelength
As frequency increases wavelength decreases
As frequency decreases wavelength increases

13. Compressional Waves
Medium travels slightly back and forth in the same direction as the energy is moving

14. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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15. Electromagnetic Waves
Waves that DO NOT require a medium for the energy to travel
Examples: Light, radio waves, x-rays, gamma rays, etc. All waves on the electromagnetic spectrum

16. Electromagnetic Waves
These waves do not need matter to travel
Difference between the different waves is wavelength
EM spectrum illustrates the differences

17. Electromagnetic Waves (cont.)
Radio – listen to your favorite station
Microwaves – call your friends
Infrared – night vision
Visible – you can see this presentation
Ultraviolet – tanning
X-ray – see broken bones
Gamma – kill cancerous cells

18. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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19. Sound
Sound is a mechanical wave (requires a medium to travel) and a compressional wave (molecules colliding)
The medium sound travels through are molecules when they collide

20. Sound Sound is produced when an object vibrates.
When an object vibrates it exerts a force on the surrounding air
Loudness of a sound is recorded in decibels
As a sound gets louder, the amplitude of the wave increases

21. Sound
The moving air mass carries the sound of the vibration to your ear.
The air is the MEDIA that it travels through.
Medium is what the wave travels through (ex. solid, liquid, gas)
NO MEDIUM NO SOUND!!!!

22. The Echo
An echo is when a sound wave hits a hard surface and bounces back, causing you to hear the sound a second time
Sonar uses echoes. It is a measure of how long it takes the echo to return to the source of the sound. Sonar can tell you how far an object is from you.

23. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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24. Speed of Sound
The speed of sound is different depending on the medium it travels through

25. Speed of Sound
Sound travels at different speeds through different medium
The more dense a material the faster sound travels
346 m/s in warm air
500 m/s in aluminum
3,240 m/s in gold

26. Speed of Sound Sound travels better through high-density materials
The closer the molecules are together, the faster they can collide and transfer energy

27. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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28. Light
Properties of Light

29. Light EM wave that travels transversely (up and down motion)
Primary colors are red, green and blue
White light is made up of all colors
Black is the absence of color

30. Light (cont.) We see colors because objects reflect light
If you see a color, that specific color is being reflected while the rest are being absorbed (taken in) by the medium
White reflects all colors
Black absorbs all colors

31. What is Light? It is a transverse wave that carries energy
It is a small part of the ElectroMagnetic Spectrum
Because it is part of the electromagnetic spectrum, it can travel through a vacuum (space)

32. How do you see the things around you?

33. Without light, there is no sight!

34. Light REFLECTS off of objects.

35. How we see
When light strikes an object the light bounces off of the object and then into our eye.
For example, the light from the this projector hits the screen and then is reflected to your eye.

36. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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37. Transparent, Translucent, Opaque

38. Opaque, Translucent, Transparent
Objects that do not let light pass through them are opaque. Ex. Walls, your desk, the science book
Objects that let light pass clearly through them are transparent. Ex. Windows, plastic wrap, eye glass lenses
Objects that let only some light pass through are translucent. Ex. waxed paper, frosted glass

39. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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40. Color

41. COLORS
The suns light might appear white, but it is a mixture of colors.
White light is produced when you mix the colors of the rainbow together.

42. Light Color Mixing
The primary colors of light are RED, BLUE and GREEN

43. So why do we see different colors?
When white light hits an object some of it may be absorbed by the object while the rest of the light is reflected. The colors we see are the reflected colors.

44. Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
Click above to be taken to that section of the Power Point