1 / 169

Light and Optics

Light and Optics. Section 1: Intro to Electromagnetic Waves. Intro Questions: What is the difference between mechanical and electromagnetic waves? Name as many types of electromagnetic waves you can What is the speed of light and any other electromagnetic wave in space?.

hoffer
Download Presentation

Light and Optics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Light and Optics

  2. Section 1: Intro to Electromagnetic Waves • Intro Questions: • What is the difference between mechanical and electromagnetic waves? • Name as many types of electromagnetic waves you can • What is the speed of light and any other electromagnetic wave in space?

  3. The Electromagnetic Wave • Characteristics: • Require no medium • Transverse waves of oscillating electromagnetic fields • Transverse waves move perpendicular to the direction the wave moves • The electric and magnetic fields are at right angles to each other • All electromagnetic waves travel at 3.0 x 108 m/s Electric Field Direction of travel towards you Magnetic Field

  4. The Electromagnetic Spectrum Wavelength Decreases Frequency Increases Energy Increases 3.0 x 108 = λ • f V = λ • f More Penetration and Dangerous Velocity = 3.0 x 108 m/s For All Electromagnetic Waves

  5. Activity 1 • Label all the parts of the electromagnetic spectrum in order of increasing frequency. • Radio Waves, Microwaves, Infrared, Visible Light, Ultra Violet, X-rays, Gamma Rays • Label the trend lines as well

  6. Activity 1 • Label all the parts of the electromagnetic spectrum in order of increasing frequency. • Radio Waves, Microwaves, Infrared, Visible Light, Ultra Violet, X-rays, Gamma Rays • Label the trend lines as well 4 Visible Light 3 Infrared 6 X-Rays 7 Gamma Rays 5 Ultra Violet 1 Radio waves 2 Microwaves Wavelength Decreases Frequency Increases Energy Increases More Penetration and Dangerous

  7. Section 2: Electromagnetic Wave Math

  8. V = λ • f Speed of light distance-time calculations • Velocity = 3.0 x 108 m/s for all electromagnetic waves • If you see any of these you have an electromagnetic wave and v = 3.0 x 108 m/s • Radio Waves, Microwaves, Infrared, Visible Light, Ultra Violet, X-rays, Gamma Rays

  9. Example 1 The AM radio band extends from 5.4 x 105 Hz to 1.7 x 106 Hz. What are the longest and shortest wavelengths in this frequency range?

  10. Example 1 The AM radio band extends from 5.4 x 105 Hz to 1.7 x 106 Hz. What are the longest and shortest wavelengths in this frequency range?

  11. Example 2 What is the frequency of an electromagnetic wave if it has a wavelength of 1.0 km?

  12. Example 2 What is the frequency of an electromagnetic wave if it has a wavelength of 1.0 km?

  13. Example 3 How long does it take for light from the sun to reach Earth if the sun is 1.5 x 1011 m away?

  14. Example 3 How long does it take for light from the sun to reach Earth if the sun is 1.5 x 1011 m away?

  15. Intro • What are the primary colors of light? • List the colors of the rainbow in order • What do all the colors of the rainbow add up to?

  16. Section 3: Visible Light and Colors

  17. Visible Light • Characteristics • “White” light is a combination of red, orange, yellow, green, cyan, blue, and violet • A prism can separate these colors out • By refraction of different wavelengths of color

  18. Visible Light 700 nm 400 nm Red orange yellow green cyan blue violet • Red: • Longest Wavelength • Lowest Frequency • Least Energy • Violet: • Shortest Wavelength • Highest Frequency • Most Energy

  19. Activity 2 • List the colors of the rainbow in order from lowest to highest frequency • Color this at home Highest Frequency Lowest Frequency ________ ________ ________ ________ ________ ________ ________ Visible Light

  20. Activity 2 • List the colors of the rainbow in order from lowest to highest frequency • Color this at home Highest Frequency Lowest Frequency Red orange yellow green cyan blue violet Visible Light

  21. Primary Colors • Red • Blue • Green Blue Red Green

  22. Blue Red Magenta • Secondary Colors: Mixture of 2 Primary Colors • Magenta (Blue and Red) • Cyan (Blue and Green) • Yellow (Red and Green) • A mixture of all three primary colors produces white light Blue Blue Green Cyan Blue Red Green Red Yellow White Green

  23. Primary Colors • Red • Blue • Green Blue Red Green

  24. Since secondary colors are a mix of two primaries: • Mixing primary and secondary colors produces white light White Light = Primary Color + Secondary Color • White Light = Blue + Yellow • White Light = Green + Magenta • White Light = Red + Cyan Blue Red Green

  25. Activity 3 • Color and label the color mixture diagram White Light = Primary Color + Secondary Color White Light= ___________+ ____________ White Light= ___________+ ____________ White Light= ___________+ ____________

  26. Activity 3 • Color and label the color mixture diagram White Light = Primary Color + Secondary Color White Light = Blue + Yellow White Light = Green + Magenta White Light = Red + Cyan White

  27. Red Blue Green Primary colors of light Primary pigments (ink) Magenta Cyan Yellow

  28. are secondary pigments Primary colors add up to white light Red • Primary colors (light) • Red • Blue • Green • Primary pigments (ink) • Magenta • Yellow • Cyan Magenta Yellow Blue Green Cyan are secondary colors Primary pigments (ink) adds up to black Yellow Green Red Cyan Magenta Blue

  29. Intro • Do section 3 of your worksheets as your intro today

  30. Section 4: Refraction of Light

  31. Optics is the science that describes the behavior and properties of light and the interaction of light with matter.

  32. Refraction- Bending of light as it travels from one medium to another. • Refraction occurs because lights velocity changes in another medium. • Light does not need a medium but it is affected by it.

  33. Key items for refraction • Light travels from the object to the observers eyes • Light travels at different speed indifferent medium • Terms to know: • Normal line • Angle of incidence Θi • Angle of refraction Θr Normal Line Θr Slower Medium Θi

  34. part of it is reflected and part is refracted • As light moves into a new medium, (a) Into slower medium light bends toward the normal line (b) Into faster medium light bends away from the normal line

  35. Objects appear to be in a different position due to refraction • An object “appears” to be straight ahead • Light always travels from the object to the observers eyes, bending into the new medium Cats Perspective Fishes Perspective

  36. Index of refraction (n)- the ratio of speed of light in a vacuum to speed of light in that substance. • Always greater than 1 because light in a vacuum is the fastest (n = 1.00 for a vacuum) • Has no unit n = index of refraction c = speed of light in a vacuum v = speed of light in medium

  37. Example 4 • Tom, a watchmaker, is interested in an old timepiece that’s been brought in for a cleaning. If light travels at 1.90 x 108 m/s in the crystal, what is the crystal’s index of refraction?

  38. Example 4 • Tom, a watchmaker, is interested in an old timepiece that’s been brought in for a cleaning. If light travels at 1.90 x 108 m/s in the crystal, what is the crystal’s index of refraction?

  39. Example 5 • How fast does light travel in fluorite (n=1.434)?

  40. Example 5 • How fast does light travel in fluorite (n=1.434)?

  41. Snell's Law- a formula that describes the angle of incidence and angle of refraction (ni)(sin Θi) = (nr)(sin Θr) ni = index of refraction of first medium (incidence side) Θi= angle of incidence nr = index of refraction of second medium (refracted side) Θr= angle of refraction

  42. (ni)(sin Θi) = (nr)(sin Θr) Can be rearranged to solve for ni Can be rearranged to solve for nr

  43. (ni)(sin Θi) = (nr)(sin Θr) Can be rearranged to solve for Θi Can be rearranged to solve for Θr

  44. Example 6 A light ray traveling through air (n=1.00) strikes a smooth, flat slab of crown glass (n=1.52) at an angle of 30.0° to the normal. • Find the angle of refraction • Draw a picture and label it

  45. Example 6 • A light ray traveling through air (n=1.00) strikes a smooth, flat slab of crown glass (n=1.52) at an angle of 30.0° to the normal. Find the angle of refraction.

  46. Example 7 Find the angle of refraction for a ray of light that enters a calm lake at an angle of 25° to the normal. (nair = 1.00 and nwater = 1.33)

  47. Example 7 Find the angle of refraction for a ray of light that enters a calm lake at an angle of 25° to the normal. (nair = 1.00 and nwater = 1.33)

  48. Section 5: Critical Angle

  49. What happens when you increase the angle of incidence when going from a slow to a fast medium? • Remember: slow to fast bends away from the normal • What happens if you increase the angle of incidence beyond here? • Total internal reflection Θr nr = 1.00 (faster) ni = 1.33 (slower) Θi

More Related