Conceptual Physics

1. Conceptual Physics Notes on Chapter 30 Lenses

2. Lenses Any piece of glass that bends parallel rays of light is a Lens

3. Lenses • If the parallel rays come together than the lens is a Converging Lens

4. Lenses • If the parallel rays spread apart, then the lens is a Diverging Lens

5. Lenses • Three rays make up the primary rays through a lens. Two are needed to form the image.

6. Lenses Major (Principal) axis - Line that runs through the center of the lens. a. Focal Point (F) is on this line. b. Focal Length is on this line. c. Center of curvature is on this line.

7. Lenses Ray #1 goes through center of lens. Ray #2 starts out parallel to lens and bends to focal point on other side of lens. Ray #3 goes through focal point to lens and then parallel to major axis.

8. Lenses • Ray #1 goes through center of lens.

9. Lenses • Ray #2 coming in horizontally from the tip of the arrow, goes through the focal point.

10. Lenses • Ray #3 going from the tip of the arrow to the near focal point will come out horizontally

11. Lenses Images If we combine the two we get the following picture.

12. Lenses REAL AND VIRTUAL IMAGES • Real images are formed when the object is far enough away to be beyond the focal point to be focused on a screen. • Virtual imagesappear to be behind the glass - but there is no light behind the glass (Mirror is a good example)

13. Lenses The Eye: • Parts • Iris • Pupil • Cornea • Retina

14. Lenses • Defects called Farsightedand Nearsightedcan cause your vision to be blurred.

15. Lenses • Farsighted people see images blurred due to lens making the image form “behind” the retina.

16. Lenses • Nearsighted people see images blurred due to lens making the image form before the retina.

17. Lenses • Other defects can be Spherical Aberration. All parallel rays do not converge to one single point.

18. Lenses • Chromatic Aberration is do to different colors and speeds in lenses.