1. Light travels in straight lines.

2. WAVE Carries energy from one place to another Classified by what they move through 1.Mechanical Waves the energy is transferred by vibrations of medium (medium = substance or material which carries the wave) ex/ ocean waves move through water 2.Electromagnetic waves (EM Waves) the energy moves through disturbances in the electromagnetic field. a disturbance that transfers energy

3. MECHANICAL WAVES travel through & gradually lose energy to that medium Examples: –water, sound, rope, & spring waves Mechanical Media: –water, air, rope, spring require a medium ( the material through which the disturbance is moving) to transmit energy Making a pulse

4. ELECTROMAGNETIC WAVES The wave, or "disturbance," is in an invisible thing called the electric force field. Examples: –Radio waves, microwaves, light, x rays, gamma rays They can travel through empty space. Don’t require a medium (the material through which the disturbance is moving) to transmit energy For more information and interactives go to http://www.colorado.edu/physics/2000/waves_particles/

5. Electromagnetic Waves They travel as vibrations in electrical and magnetic fields. Have some magnetic and some electrical properties to them. Called transverse waves, wave motion is perpendicular to the direction the energy moves –http://einstein.byu.edu/~masong/htmstuff/WaveTrans.htmlhttp://einstein.byu.edu/~masong/htmstuff/WaveTrans.html –http://hermes.ffn.ub.es/~albert/ones/wavemotion.htmlhttp://hermes.ffn.ub.es/~albert/ones/wavemotion.html

6. Electromagnetic Waves

7. Light is an electromagnetic wave A transverse wave that does not require a medium, therefore it can travel through space Light can travel through certain media Light is part of a range of electromagnetic waves known as the electromagnetic spectrum

8. TRANSVERSE WAVE STRUCTURE CREST (peak) AMPLITUDE resting to max peak WAVELENGTH TROUGH

9. CHARACTERISTICS OF TRANSVERSE WAVES Waves are described according to their Amplitude measures DISPLACEMENT size of the disturbance Wavelength distance of a “repeating unit” Also called a cycle Velocity v speed = how fast wave travels

10. AMPLITUDE –Distance between “rest & crest” or “rest & trough” –Gives indication of “power” or “strength” of wave (magnitude of earthquake = Richter scale) –Does not affect velocity of wave –Determines loudness (sound) or brightness (EM wave)

11. WAVELENGTH Distance between any two repeating points on a wave crest-crest, trough-trough, expansion-expansion, compression-compression Determines what colors we see; what notes we hear (pitch) Shorter wavelengths have more cycles per minute because they aren’t as long

12. VELOCITY v Rate at which the energy travels; speed & direction Depends on medium –Mechanical waves travel faster through dense mediums –EM Waves are faster through less dense mediums

13. FREQUENCY ƒ measured in wavelengths/second or cycles/second Hertz (Hz) = number of wavelengths in 1 second Frequency is related to velocity: v = ƒ  How often number of wavelengths that pass any point per second

14. Electromagnetic waves travel VERY FAST – around 300,000 kilometres per second (the speed of light in a vacuum ). At this speed they can go around the world 8 times in one second. Speed of Electromagnetic waves

15. Wavelength and frequency Speed of light in any medium is a constant Speed = wavelength x frequency Large wavelength = low frequency Small wavelength = high frequency

16. Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency

17. Notice the wavelength is long (Radio waves) and gets shorter (Gamma Rays)

18. RADIO WAVES Have the longest wavelengths and lowest frequencies of all the electromagnetic waves.

19. Global Positioning Systems (GPS) measure the time it takes a radio wave to travel from several satellites to the receiver, determining the distance to each satellite.

20. A radio picks up radio waves through an antenna and converts it to sound waves. –Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency.

21. MRI (MAGNETIC RESONACE IMAGING) Uses Short wave radio waves with a magnet to create an image.

22. MICROWAVES Have the shortest wavelengths and the highest frequency of the radio waves.

23. Used in microwave ovens. Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food. MICROWAVES

24. INFRARED RAYS Infrared= below red Shorter wavelength and higher frequency than microwaves.

25. INFRARED RAYS You can feel the longest ones as warmth on your skin Warm objects give off more heat energy than cool objects.

26. VISIBLE LIGHT Shorter wavelength and higher frequency than infrared rays. Electromagnetic waves we can see. Longest wavelength= red light Shortest wavelength= violet (purple) light

27. When light enters a new medium it bends (refracts). Each wavelength bends a different amount, allowing white light to separate into it’s various colors ROYGBIV.

28. ULTRAVIOLET RAYS Shorter wavelength and higher frequency than visible light Carry more energy than visible light

29. Used to kill bacteria. (Sterilization of equipment)

30. Too much can cause skin cancer. Use sun block to protect against (UV rays)

31. Causes your skin to produce Vitamin D (good for teeth and bones)

32. X- RAYS Shorter wavelength and higher frequency than UV-rays Carry a great amount of energy Can penetrate most matter.

33. Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)

34. Too much exposure can cause cancer (lead vest at dentist protects organs from unnecessary exposure)

35. Used by engineers to check for tiny cracks in structures. –The rays pass through the cracks and the cracks appear dark on film.

36. GAMMA RAYS Shorter wavelength and higher frequency than X- rays Carry the greatest amount of energy and penetrate the most.

37. Used in radiation treatment to kill cancer cells. Can be very harmful if not used correctly.

38. Exploding nuclear weapons emit gamma rays.

39. Brief Summary A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second) in a vacuum. B. They all have different wavelengths and different frequencies. –Long wavelength-  lowest frequency –Short wavelength  highest frequency –The higher the frequency the higher the energy.

40. Visible spectrum Wavelength of visible light ranges from 700nm to 400nm. nm = nanometer (10 -9 m) or 0.0000007m to 0.0000004m

41. Spectrophotometer Wavelength dial Wavelength window

42. Transparent An object that lets all light pass through it is called transparent. These objects are transparent: clear glass, eyeglasses, window, fish tank, clear plastics, and transparent tape.

43. Translucent An object that lets some light pass through it is called translucent. These objects are translucent: waxed paper, sunglasses, frosted glass, and thin fabrics.

44. Opaque An object that lets no light pass through it is called opaque. These objects are opaque: rock, metal, wood, fog, aluminum foil, thick paper, and brick.

45. Refraction Light interacts with transparent media and refracts or bends Refraction of light occurs whenever light travels from one transparent medium into another Light waves travel at different speeds through different media

46. Refraction Light waves travel at different speeds through different media when the light changes speeds, it bends

47. Refraction

48. Index of Refraction The “light slowing factor” is called the index of refraction (n) –glass has n = 1.52, meaning that light travels about 1.5 times slower in glass than in vacuum –water has n = 1.33 –air has n = 1.00028 –vacuum is n = 1.00000 (speed of light at full capacity)

49. Index of Refraction The larger the index of refraction, the slower the speed of light in the medium The larger the index of refraction, the more the light bends (the bigger the difference between the angle of incidence and the angle of refraction)

50. Refraction at a plane surface Light bends at interface between two media Measure the angles from the normal line (N) I=Incidence R=Refraction

51. Refraction at a plane surface Light bends and makes the straw look broken or the root beer glass look thinner than it is (when the glass is in water, you can see how thick it really is)

52. Convex Lenses Thicker in the center than edges. –Lens that converges (brings together) light rays. –Magnifies a flat image

53. Concave Lenses Lenses that are thicker at the edges and thinner in the center. –Diverges light rays –Reduces an image

54. Refraction of light through flat plastic What the lines really look like. What the lines look like when viewed through an acrylic semicircle placed between points A and B

55. Refraction of light through concave or convex lenses What the lines really look like. What the lines look like when viewed through an convex or concave lenses placed between points A and B

56. Reflections Reflect is when light or an image bounces back off an object’s surface. Light can bounce back off an opaque object.

57. Law of Reflection Light travels in straight lines Reflection off a flat surface follows a simple rule: –angle in (incidence) equals angle out (reflection) –angles measured from surface “normal” (perpendicular)

58. Reflection Measure the angles from the normal line i = Angle of Incidence r = Angle of refraction

59. Color Make a Splash with Color http://www.thetech.org/exhibits/online/color/overview/ http://www.thetech.org/exhibits/online/color/overview/ What wavelength goes with which color? http://science- edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html

60. Color of transparent materials Light passes through transparent materials Some transparent materials absorb certain wavelengths of light and transmit others, the color we see depends on the wavelengths that are transmitted The more light that is absorbed, the less light is transmitted and vice versa

61. Color of opaque objects The color an opaque object appears depends on the colors of light it absorbs and reflects. For example, a red book only reflects red light. It absorbs all the other wavelengths of visible light. White light Only red light is reflected

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

63. Using colored light If we look at a colored object in colored light we see something different. For example: White light Shorts look blue Shirt looks red

64. In different colors of light things would look different: Red light Shirt looks red Shorts look black (Blue shorts absorb red light) Blue light Shirt looks black (Red shirt absorbs blue light Shorts look blue

65. Using filters Filters can be used to “block” out different colors of light: Red Filter Magenta Filter

66. Torgerson, E. "Light reflect refract absorb abel." Mr. Torgerson's Science Daily Agenda. WordPress, 2011. Web. 1 Feb. 2015.