1. PH 103 Dr. Cecilia Vogel Lecture 6 NO QUIZDOM TODAY

2. Review Outline  Lenses  using thin lens equation  ray diagrams  Lenses  types  focal point  Images  thin lens equation

3. Lens Equations and Sign Conventions  d o = object distance  positive for real object, in front  + for any real physical object  negative if virtual, behind  d i = image distance  positive for real image, behind  negative for virtual image, in front  f = focal length  positive if converging  negative if diverging  Thin lens equation

4. Magnification Equation and Sign Conventions  h o & h i = object & image height  positive if upright  negative if inverted  M = magnification  positive if lens makes an image that is same side up as object  negative if lens inverts image

5. Rubric for Ray Diagrams  Neatness, clarity, distances drawn to scale  Show appropriate type of lens  One end of object and of image on axis  Label object, image, and focal point(s)  Accurately draw at least two rays*  Where the ray actually goes, draw solid line  otherwise dashed line  Accurately find image  position, size, orientation

6. * Accurately draw at least two rays  M-ray (middle or central ray)  at the center of lenses, the two surfaces are parallel  light passes thru just like it would a window pane  M-ray from object passes straight thru center of lens

7. * Accurately draw at least two rays cont’d  P-ray (parallel or principle ray)  what happens to a ray that approaches lens parallel to axis?  depends on type of lens  P-ray for converging lens  comes from object to lens parallel to axis  then converges toward the axis, passing thru focal point behind lens  P-ray for diverging lens  comes from object to lens parallel to axis  then diverges away from the axis, on line with (but not thru) focal point in front of lens

8.  Examples on board  f = +25 cm, d o = 75 cm,  f = +25 cm, d o = 10 cm,  f = -25 cm, d o = 55 cm,  Check out Java appletJava applet  Draw diagram to find image position and size  Also calculate example answers:  image distance  and magnification Ray Diagrams