1. Thin Lenses

2. Two Types of Lenses Converging – Thicker in the middle than on the edges FOCAL LENGTH (+) POSITIVE Produces both real and virtual images Diverging – Thinner in the middle than on the edges FOCAL LENGTH (-) NEGATIVE Produces only virtual images

3. What’s so Great about Lenses? SAME EQUATIONS! SAME RULES FOR DRAWING RAY DIAGRAMS!

4. Rules for Ray Diagram for Lenses RayFrom object to lensFrom converging lens to image From diverging lens to image Parallel RayParallel to principal axis Passes through focal point, F Directed away from focal point, F Central RayTo the center of the lens From the center of the lens Focal RayPasses through focal point, F Parallel to principal axis

5. Ray Diagram for Converging Lens

6. Ray Diagram for Diverging Lens

7. Same Formulas as Mirrors! positivereal negativevirtual negativeInverted positiveUpright Image Distance: Magnification / image height:

8. Sign Conventions for Lenses Negative Distance Positive Distance Positive Height Negative Height

9. An object placed 12.5cm in front of a diverging lens. The lens has a focal length of 10.0 cm. Find the image distance and the magnification.