1. Lecture 17 Ray Optics-3 Chapter 23 PHYSICS 270 Dennis Papadopoulos March 22, 2010

3. Total Internal Reflection

5. Image by Refraction

6. EXAMPLE 23.13 A goldfish in a bowl

7. What is a lens? Device that provides a capability to create bright and well focused images. How? Use Refraction to create images out of divergent light rays Focal point Focal length Property of lens no matter how it is used Distance from lens that paraxial rays converge Reversibility

8. Converging and Diverging Lenses

9. Thin Lenses – Real Image –Special Rays Thin lens-> d<<f,s,s’ Inverted Image

10. Thin Lenses: Ray Tracing

11. Tactics: Ray tracing for a converging lens

13. Lateral Magnification The image can be either larger or smaller than the object, depending on the location and focal length of the lens. The lateral magnification m is defined as 1.A positive value of m indicates that the image is upright relative to the object. A negative value of m indicates that the image is inverted relative to the object. 2.The absolute value of m gives the size ratio of the image and object: h'/h = |m|.

14. s>f  h’/h=s’/s

15. Virtual Image s’ 0 image upright

16. EXAMPLE 23.10 Magnifying a flower s<f

17. Diverging Lenses Thicker at the edges Demagnification

18. Diverging lenses Ray Tracing