1. ????

2. Refraction

3. Refraction: Essential Questions What is refraction? What causes refraction? What are some examples of refraction of light that show why it is important?

4. Refraction of Light - Defined Refraction of light occurs when a light wave moves from a vacuum (or a medium) into another medium (or a vacuum). When a wave changes media, its ____________ changes. Unless the barrier between the media is perpendicular to the movement of the wave, the wave will change direction – that is REFRACTION

5. Refraction Illustrated

7. Refraction & Mirages

8. Refraction & Dispersion

9. Lenses: What do we want to know?

10. Color Practice Question: In a darkened room, yellow light is aimed at a cyan piece of paper. What color does the paper appear? Explain.

11. What do we need to know about lenses? Can we compute: f, d i What affects f? What shape will produce real images? What shape do we used for near-sighted vs far-sighted? What do near and far sighted mean?

12. Lenses

14. Ray Diagrams Convex (Converging) for Lenses

15. Ray Diagrams for Convex (Converge) Lenses 1.From tip of object, draw a ray that is parallel to the P.A. When it hits the lens, it refracts thru the (far) focal point 2.From the tip of the object, go straight thru the center of the lens w/o bending. 3.From the tip of the object, draw a ray thru the near focal point. When it hits the lens it refracts parallel to the P.A.

16. Practice Draw the ray diagrams for #1-3 on the WS Draw the image Measure d i

17. The Thin Lens Equations 1/f = 1/d o + 1/d i f = focal length is dependent on curvature and material lens is made of d o = object distance d i = image distance The image is real, inverted, and on the other side of the lens than the object when d o > f The image is virtual, upright, & on same side of the lens as the object when d o < f

18. Thin Lens Example: A 2.00cm tall flame held 20.0cm from a thin convex lens projects a focused image on a screen that is 60.0cm from the lens. a) What is the focal length of the lens? b) What height is the image?

19. Determine the focal length of a convex lens. Perform ONE trial per person in your group. Each individual computes f for one of the trials, showing all steps as in a word problem. Compute average f for all trials. Report Objective: Materials Diagram: LABLED Data: IN A TABLE WITH HEADINGS AND UNITS Analysis: ONE PER MEMBER OF GROUP Conclusion: AVERAGE RESULT STATED IN A SENTENCE

20. Individual Practice Assignment On the back of the WS “Ray Diagrams”, solve #1-3 using the “thin lens” formula