1 Physics 7C SS1, Lecture 6: Ray Model Lenses & Images

2 Agenda Quiz 2 Review Ray model: lenses and images Introduce Field model: Electric field and Force Analogies with gravitational field and force

3 Quiz 2

4 Lecture today should be… a)Primarily about lenses b)More lenses than fields c)Even between lenses and fields d)More fields than lenses e)Primarily about fields

5 Every part of the tree reflects light, scattering it all directions. A ray diagram is used to simplify this picture.

6 What type of image does Ernie make? a)Real b)Virtual c)Upright d)Inverted e)Bigger f)Smaller

7 c Focal point, f Object plane Image plane oi

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9 c Focal point, f Object plane o i Image plane

10 Where will the image be? How big will the image be?

11 Terms in Optics Concepts: Object Image Real Virtual Upright Inverted Magnification Focus Ways to locate Image: Thin Lens Equation Image distance Object distance Sign of lens Ray Tracing Principal Rays Lens Types: Converging Diverging Convex Concave

12 c Image plane True/False: This is enough information to determine the focal point of the lens. If true, devise a procedure. If false, determine the minimal additional information necessary. Image Object

13 You place a tiny source of light at the focal point What happens? a)Rays all bend through the far focal point b)Rays emerge parallel c)Rays travel straight (looks like diverge from the near focal point) d)Something else