Wednesday, April 24 Reminders: Big test tomorrow! Chapters 25-31 - Sound & Light Your entire portfolio is due tomorrow. Be sure you've turned in the lab from Monday and Chapter 31 Diffraction and Interference Questions from yesterday.

Chapter 29 Review Questions, # 1-21 assigned on Wednesday, April 10 5 points possible Answers: 1. It reverses direction and goes back through the original medium; part goes into the second medium. 2. They reflect almost all the colors of visible light. 3. 4%; 96% (at first surface) 4. Any line that is perpendicular to the surface. 5. Angle of incidence = angle of reflection.

Chapter 29 Review Questions, #1-21 continued 6. Same distance 7. Yes, but the normals at different points are not parallel to one another. 8. Yes, each single ray obeys the law of reflection. 9. The surface is considered polished if its irregularities are less than 1/8 the wavelength of the incident wave. 10. Echo - single reflection; reverberation - multiple reflections 11. Yes, and for all other types of waves.

12. Reflection -- waves bounce off of surface and travel back into the original medium; refraction -- waves enter a new medium and change direction. 13. Different parts of the wave change speed at different times. 14. Perpendicular 15. Abrupt -- light traveling from air to water (sharp boundary); gradual -- light traveling into the atmosphere.

16. Yes, and for all other types of waves. 17. No, refraction depends on change in wave speed. 18. Yes (eyes, at least). The directions of rays are reversible. 19. Shallower 20. Refraction. It only appears to be a reflection. 21. Longer by a few minutes

Today's warm-up You will take a little practice test for Chapters 25- 31. You may use your portfolio and notebook on this. This is only a small sample of possible questions that will be on tomorrow's BIG test.

Now that you've completed the practice test, Check your work with the person sitting next to you. Use the book, your portfolios, and notebooks to verify answers. Discuss your answers and correct your work. The material covers Chapters 25-31

Have I got a deal for YOU!!! For tomorrow's test You may use this time to work with a partner and create a "Test Helper" study sheet: Use a lined sheet of paper Title it "Test Helper Chapters 25-31" and put your name on it. Write any pertinent information from Chapters 25-31 on only one side of it. You may use this on the test. You must turn it at the end of the test for credit (yes, this is an assignment). Remember: portfolios are due tomorrow

Chapter 31: Diffraction and Interference Questions 1. Waves spread out when they pass through an opening. Does spreading become more or less pronounced for narrower openings? Explain. More pronounced 2. What is this spreading of waves called? diffraction

3. Does diffraction aid or hinder radio reception? It aids reception because the spreading causes the waves to reach more places. 4. Does diffraction aid or hinder the viewing of images in a microscope? It hinders the viewing because the spreading of waves blurs the image. 5. What is a diffraction grating? A surface with many parallel slits to diffract light.

6. a. What is iridescence, and to what phenomenon is it related? Display of colors produced by interference. b. Examples of iridescence: soap bubbles, gasoline spilled on wet road, surface of CD 7. If a soap bubble is thick enough to cancel yellow by interference, what color will it appear if illuminated by white light? Its complementary color, blue

8. Why is gasoline that is spilled on a wet surface so colorful? Interference of light reflected from gasoline and water surfaces. 9. How does light from a laser differ from light from an ordinary lamp? It is coherent, monochromatic, and in phase. 10. What is a hologram and how is it produced? A 3-D photograph; interference between laser beams

11. How does the image of a hologram differ from that of a common photograph? It is a 3-D image with limited parallax. 12. What would be the advantage of making holograms with X-rays? The image would be magnified in the same proportion as the wavelengths.