2. 10.7 – THIN CONVEX LENSES Also called, why the human eye is spherical instead of flat.

3. EVER WONDERED…?

4. OBJECTIVES WWBAT…  Describe how an image is formed by a thin convex lens  Determine the location of image formation for a thin convex lens  Determine the magnification of an image for a thin convex lens  Determine whether or not an image is upright or inverted for a thin convex lens  Determine whether an image is real or virtual for a thin convex lens

5. IMAGE FORMATION BY REFRACTION IN THIN CONVEX LENSES  Convex: bending outward  Thin convex lenses are also called biconvex or converging  Light rays from an object are refracted and converge to form a real image beyond the lens

6. FOCAL LENGTH  The focal length of a thin convex lens is the point beyond the lens where all head-on light rays converge when refracted  This is not where the image forms, however!

7. HOW TO PREDICT IMAGE FORMATION FOR THIN CONVEX LENSES Questions to ask  Where does the image form?  Is the image upright or inverted (upside down)?  Is the image larger or smaller than the original image?

8. RAY DIAGRAMS FOR THIN CONVEX LENSES

12. Check out the PhET Virtual Lab on the course website!

13. A TRICKY EXAMPLE…

16. AN EVEN TRICKIER EXAMPLE…

17. THE FIVE CASES Image beyond 2F Image at 2FImage between F and 2F Image at FImage closer to lens than F Real image Inverted Smaller Real image Inverted Same size Real image Inverted Larger No image formsVirtual image Upright Larger

18. CHECK YOURSELF #1

20. MATH OF IMAGE FORMATION

21. Possible Outcome What it means d i is negative Virtual image; image forms on same side of lens h i or M is negative Real image (inverted)

22. A 4.00-cm tall light bulb is placed a distance of 45.7 cm from a double convex lens having a focal length of 15.2 cm. Determine the image distance and the image size. Image DistanceImage Size

23. A 4.00-cm tall light bulb is placed a distance of 45.7 cm from a double convex lens having a focal length of 15.2 cm. Determine the image distance and the image size. Image DistanceImage Size

24. A 4.00-cm tall light bulb is placed a distance of 45.7 cm from a double convex lens having a focal length of 15.2 cm. Determine the image distance and the image size. Image DistanceImage Size

25. A 4.00-cm tall light bulb is placed a distance of 45.7 cm from a double convex lens having a focal length of 15.2 cm. Determine the image distance and the image size. Image DistanceImage Size

26. YOU TRY 4.00-cm tall light bulb is placed a distance of 8.30 cm from a double convex lens having a focal length of 15.2 cm. (NOTE: this is the same object and the same lens, only this time the object is placed closer to the lens.) Determine the image distance and the image size.

27. YOU TRY 4.00-cm tall light bulb is placed a distance of 8.30 cm from a double convex lens having a focal length of 15.2 cm. (NOTE: this is the same object and the same lens, only this time the object is placed closer to the lens.) Determine the image distance and the image size. Image DistanceImage Size

28. OBJECTIVES WWBAT…  Describe how an image is formed by a thin convex lens  Determine the location of image formation for a thin convex lens  Determine the magnification of an image for a thin convex lens  Determine whether or not an image is upright or inverted for a thin convex lens  Determine whether an image is real or virtual for a thin convex lens

29. STILL WANT MORE? Extra resources on the website about how the eye works!