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# Science8 Unit C Lightand Optics Section2 Lesson4 Mirrors Lensesand Refraction [Autosaved]

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Law of Refraction
Convex and Concave Lenses
Convex and Concave Mirrors
Diamonds
Mirage

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• ### Transcript of "Science8 Unit C Lightand Optics Section2 Lesson4 Mirrors Lensesand Refraction [Autosaved]"

1. 1. Sections 2.3-2.5 Pages 197-211
2. 2. <ul><li>Section 2.3 </li></ul><ul><li>Pages 197 to 199 </li></ul><ul><li>Learner Outcome </li></ul><ul><li>I can demonstrate the formation of images through the use of curved mirrors </li></ul>Keck Observatory: Hawaii 10 m wide concave mirror
3. 3. <ul><li>Concave mirror – has a surface that curves inward like a bowl </li></ul><ul><li>Parallel light rays that hit the concave mirror will reflect at a common point called the focal point . </li></ul><ul><li>Good for reflecting telescopes where you want to gather as much dim light as possible </li></ul>
4. 5. <ul><li>If the image is far away from the focal point, the reflected rays form an upside-down image. </li></ul><ul><li>The closer the object gets to the focal point, the larger the image becomes. </li></ul><ul><li>If the object is between the focal point and the mirror, the image becomes upright and enlarged . </li></ul><ul><li>Page 198 for diagram </li></ul>
5. 12. <ul><li>Convex mirror – surface is curved outward </li></ul><ul><li>Spreads out the light rays making images appear from a smaller point behind the mirror </li></ul>
6. 16. <ul><li>Read page 198 and complete the activity </li></ul><ul><li>Make your hypothesis and prediction </li></ul><ul><li>Make sure you record your observations accurately </li></ul><ul><li>After you are finished, try repeating the exercise with a convex mirror </li></ul><ul><li>Answer the same questions, except using a convex mirror </li></ul>
7. 17. <ul><li>… demonstrate the formation of images through the use of curved mirrors? </li></ul>
8. 18. <ul><li>Questions 1 to 5, page 199 </li></ul><ul><li>Page 199 </li></ul><ul><li>Sample Example question. </li></ul><ul><li>Explain how mirrors in telescopes work to enhance our knowledge of the universe ? </li></ul>
9. 19. <ul><li>#1. Do curved mirrors obey the law of reflection? Explain your answer. </li></ul><ul><li>_________________________________________________________________________________________________________________________________________________ </li></ul><ul><li>#2. Someone has left a shiny metal bowl outside in the sun. Which may have the potential to damage your eyes: looking at the outside of the bowl or the inside? Explain. </li></ul><ul><li>_________________________________________________________________________________________________________________________________________________ </li></ul>
10. 20. <ul><li>#3. An object is held extremely close to a concave mirror. Describe how the image will appear. Draw a ray diagram to explain. </li></ul><ul><li>__________________________________________________________________________________________________________________________________ </li></ul>
11. 21. <ul><li>#4. If you look in at a convex mirror, would your image ever appear smaller? Explain why or why not. </li></ul><ul><li>______________________________________________________________________________________________________________________________________________________________ </li></ul><ul><li>#5. Describe a practical use of a convex and concave mirror. </li></ul><ul><li>______________________________________________________________________________________________________________________________________________________________ </li></ul>
12. 22. <ul><li>Section 2.4 </li></ul><ul><li>Pages 200 to 203 </li></ul><ul><li>Learner Outcome </li></ul><ul><li>I can investigate, measure and describe the refraction of light through different materials . </li></ul>
13. 23. <ul><li>Light bends when it leaves the water. </li></ul><ul><li>When the light ray strikes a boundary where two different substances meet ( the interface ) at an angle, it will change direction. </li></ul><ul><li>Page 200 </li></ul>
14. 24. <ul><li>Refraction is due to changes in the speed of light. </li></ul><ul><li>Light slows down as it enters different mediums. </li></ul><ul><li>The denser the medium, the more light will slow down and the angle of refraction will be more. </li></ul>
15. 25. <ul><li>Light travels slower in materials that are denser, because there are more particles . </li></ul>
16. 26. <ul><li>The Law of Refraction … when light travels from one medium, to a more dense medium , the light will be bent toward the normal, and when it exits the denser medium into a less dense medium it will bend away from the normal. The new direction of light is called the angle of refraction. </li></ul>
17. 27. <ul><li>Light slows down as it enters a diamond. </li></ul><ul><li>Why? </li></ul><ul><li>Answer: Density </li></ul>
18. 28.   Light Emission A well-cut diamond will reflect most of the light back to the observer's eye. A poorly cut diamond will reflect only a small proportion of the light that enters it.                                                                                                                                                                     Well cut diamond - most light is reflected back to the observer. Cut too deep; pavilion is too thick - most light is lost through the side of the stone. Cut too shallow; pavilion too flat - most light is lost through the bottom of the stone.
19. 29. <ul><li>Refraction can also occur when light travels through air at different temperatures , because warm air is less dense than cold air. </li></ul><ul><li>The refraction of light through air is called a mirage . </li></ul>
20. 30. Type of behaviour What happens to light striking a surface Nature of surface What else happens? Absorption Energy Transformation rough, dark, opaque some light is reflected Reflection Bounces off smooth, shiny some light is absorbed Refraction Travels through in a new direction different transparent medium some light is reflected
21. 31. <ul><li>… investigate, measure and describe the refraction of light through different materials ? </li></ul>
22. 32. <ul><li>Questions 1 to 4, page 203 </li></ul><ul><li>Sample Exam Question </li></ul><ul><li>What is the angle of refraction in a gemstone if the incoming angle (incidence) is 45 degrees and the angle inside the gem to the NORMAL outside the gem is 150 degrees? </li></ul>
23. 33. <ul><li>#1. What happens to light rays when they pass from one medium into another medium? Explain the process of refraction. </li></ul><ul><li>______________________________________________________________________________________________________________________________________ </li></ul><ul><li>#2. How does the type of medium affect refraction? </li></ul><ul><li>______________________________________________________________________________________________________________________________________ </li></ul>
24. 34. <ul><li>#3. When would it be easier for a bear to catch a fish (river trout): as the fish swims or when it jumps in the air? Use your knowledge of how light travels in air and water to explain. </li></ul><ul><li>______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ </li></ul>
25. 35. <ul><li>#4. Why do objects at the bottom of an aquarium filled with water appear closer than they actually appear? </li></ul><ul><li>______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ </li></ul>
26. 36. <ul><li>Section 2.5 </li></ul><ul><li>Pages 204 to 208 </li></ul><ul><li>Learner Outcome </li></ul><ul><li>I can demonstrate the formation of real images, using a double convex lens, and predict the effects of changes in the lens position on the size and location of images </li></ul>
27. 37. <ul><li>Concave lens is thinner in the center than at the edges. </li></ul><ul><li>Light is refracted away from the center of the lens. </li></ul><ul><li>The light rays will never meet on the other side of the lens. </li></ul>
28. 39. <ul><li>Convex lens curves outward and is thicker in the middle than at the edges. </li></ul><ul><li>Often called a double convex lens </li></ul><ul><li>Light rays are reflected toward the center of the lens and meet at the focal point . </li></ul><ul><li>Acts as a light collector . </li></ul><ul><li>Forms a real image – projected </li></ul><ul><li>Images can be smaller or larger than the object but are upside down </li></ul>
29. 44. See page 208 for more details on moving the object and lens
30. 45. <ul><li>… demonstrate the formation of real images, using a double convex lens, and predict the effects of changes in the lens position on the size and location of images ? </li></ul>
31. 46. <ul><li>Questions 1 to 5, Page 208 </li></ul><ul><li>Sample Example question </li></ul><ul><li>Convex lenses </li></ul><ul><li>Diverge light </li></ul><ul><li>Converge light </li></ul><ul><li>Reflect light </li></ul><ul><li>Separate light into colors </li></ul>
32. 47. <ul><li>#1. Why are lenses useful for moving light around? ____________________________________________________________________________________________________________________________________ </li></ul><ul><li>#2. Draw a ray diagram that shows the path light rays take through a concave lens. </li></ul>
33. 48. <ul><li>#3. What kind of image is formed when an object is placed at the focal point of convex lens? ____________________________________________________________________________________________________________________________________ </li></ul><ul><li>#4. Use Figure 2.32 on page 208 to help you. </li></ul><ul><li>How do the bricks let light through but still protect your privacy? </li></ul><ul><li>____________________________________________________________________________________________________________________________________ </li></ul>
34. 49. <ul><li>#5. Suppose you wanted to examine closely the leaf of a plant. What type of lens would you choose. Would you use a lens combination? Explain. </li></ul><ul><li>__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ </li></ul>
35. 50. <ul><li>Questions 1, 2, 4 to 8, Page 211 </li></ul><ul><li>The Nature of Science </li></ul><ul><li>Questions 1-3 </li></ul><ul><li>Study for your Section 2.0 Quiz </li></ul>
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