1. LENSES AND THE FORMATION OF IMAGES

2. Lenses We see the world through lenses… Eye glasses = lenses Contacts = lenses Magnifying glasses = lenses Microscopes = lenses Camera = lenses

3. Lenses What about individuals that do not need visual aids? They still see the world though the lenses in their eyes

4. Lenses Lenses consist of two basic shapes 1.Convex or converging lenses 2.Concave or diverging lenses

5. Convex Lenses A lens that is thickest in the middle Causes incident parallel light rays to converge (meet) through a single point after refraction The thicker the lens, the smaller the focal length

6. Concave Lenses A lens that is thinnest in the middle Causes incident parallel light rays to diverge (spread apart) after refraction The thicker the lens, the smaller the focal length

7. Refraction There are always two refractions in a lens First at the air to glass boundary, then at the glass to air boundary

8. Refraction However, we will simplify our ray diagrams by adding a central line and show light being refracted only once