1. Electromagnetic Radiation

2. What is light? Wave theory Light travels in waves Is reflects off objects It can pass through other light Particles would bounce off each other It converts to other energy

3. What is light? Particle theory Light travels as particles Light travels in straight lines. Light can travel through a vacuum Light does not diffract shadows

4. What is light? Particle / wave theory Light is a particle with the properties of a wave

5. Light The energy produced by the vibrations of electrically charged particles e−e−

6. e−e−

7. e−e− Photon of light

19. Microwave

20. Microwave (Radar)

23. Infrared

25. Visible Light

28. Ultraviolet

35. Speed of Light Sound travels at approximately 343 m/s Light travels at 300,000 km/s That’s 180,000 miles per second The Earth’s circumference is 25,000 miles Light could travel around the Earth 7.2 times in one second

36. Speed of Light The sun is 93,000,000 miles away It takes light from the sun 8.3 minutes to get to Earth The distance from the sun to Neptune is 2,800,000,000 miles from the sun It takes light from the sun 4.17 hours to reach Neptune The closest star to Earth (Proxima Centarui) is 25,000,000,000,000 miles from Earth Light takes 4.25 years to reach there

38.  Reflection  Light bounces off a surface  Law of Reflection  - The angle of incident equals the angle of reflection

39. 42° Incident beam Reflection beam

40. 20° Incident beam Reflection beam

41.  Reflection  Light bounces off a surface  Two types of reflection  Regular

42.  Two types of reflection  Regular  Diffused

43.  Reflection or light Source?  Objects that produce light are said to be luminous

44.  Objects that are visible because light is reflected off of them are said to be illuminated.

45. Scattering When light interacts with matter and changes direction by frequency Each frequency of light reflects in a different direction What makes the sky look blue? Blue light tends to scatter downward so when we look up into the air we see more blue light.

46.  Absorption  When the energy of light is transferred to particles of matter  This is why you feel warmer in dark clothes

47. Refraction The bending of a wave as it passes between two substances in which the speed differs

48. Refraction The bending of a wave as it passes between two substances in which the speed differs

49. Refraction When light moves from one medium to another. The different frequencies bend at different rates. v

50. Rainbows When light interacts with water in the atmosphere and refracts. Each frequency of light refracts at a different rate and we see the difference as the colors of the rainbow.

52. Refraction

58. He should have paid attention in science class. Ha ha!

59. Diffraction The change in direction of a wave when it finds the edge of an obstacle. At first we though that light did not diffract because we saw shadows Light does diffract but only slightly

60. Interference Constructive Light gets brighter Destructive Light gets dimmer? Is the light eliminated? Light is made of particle that are so small and vibrate so fast that even when they do interfere destructively, we can’t see it.

61. Light Interacting with Matter How light interacts with matter Reflection Absorption Transmission

62. Reflection Light energy “bounces” off the object Absorption Light energy is converted to thermal energy Transmission When light energy passes through matter Example Glass Light reflects off the glass Some light is absorbed Some light passes through

63.  Reflection  Light bounces off a surface

64.  Absorption  When the energy of light is transferred to particles  This is why you feel warmer in dark clothes

65.  Transition  The movement of light through an object

66. Types of Matter Transparent Light transmits right through Translucent Light transmits through but it is scattered Opaque Light does not transmit through

67. Light and Color

68. Color Color of opaque objects Some frequencies of light are absorbed Some frequencies are reflected It is the reflected colors that we see What ever that frequency is, is the color we see

69. Color of transparent or translucent objects Some frequencies of light are absorbed Some frequencies are transmitted It is the color of the transmitted light that we see

70. Primary Colors of Light We get white light by mixing all the colors of light together This is called an additive property The three primary colors are Red Green Blue When mixed they make every other color of light

82. Primary Colors of Pigment Pigment is a substance that absorbs light When we add pigment we move farther away from white and closer to black This is called a subtractive property The three primary colors of pigment are Magenta Cyan Yellow When mixed together they make black

83. Light / Sound Interactions Reflection Light “bounces off Diffraction Light bends slightly as it reaches the edge of a barrier Refraction Light bends as it moves from one medium to another and changes speed

84. Light / Sound Interactions Refraction Light bends as it moves from one medium to another and changes speed Interference Constructive Crests and troughs line up and the amplitude increases Destructive Crests and troughs do not line up and the amplitude decreases

87. Constructive Interference

88. Interference of sound Destructive When crest and troughs do not line up

91. Destructive Interference

96.  It is the combination of constructive and destructive interference that make sounds unique.

97. Violin

98. Guitar

99. Horn