1. Lenses Lenses do all the same things mirrors do and use all the same terms and variables. Lenses do all the same things mirrors do and use all the same terms and variables. The only difference between a lens and a mirror is light goes through a lens, instead of being reflected. The only difference between a lens and a mirror is light goes through a lens, instead of being reflected. real images and focal points occur on the opposite side as a real object. real images and focal points occur on the opposite side as a real object. since light can come from either side there are technically 2 focal points (one on each side) since light can come from either side there are technically 2 focal points (one on each side)

2. Types of lenses Concave Lens (Diverging Lens) (virtual) focal point Convex Lens (converging lens) focal point The virtual and real side flip for the focal point!

3. Ray Diagrams for lenses You could also use the same equation “1/f = 1/q + 1/p” to do it algebraically, but we won’t have to. You could also use the same equation “1/f = 1/q + 1/p” to do it algebraically, but we won’t have to. It gets tricky because of what is real (+) and virtual (-). It gets tricky because of what is real (+) and virtual (-).

4. Rules for Ray Diagramming Lenses You must draw 3 rays You must draw 3 rays 1. parallel to a perpendicular of the lens, continues through appropriate F 1. parallel to a perpendicular of the lens, continues through appropriate F 2. through near F for convex or what would be through far F for concave (it won’t make it there), continues parallel to a perpendicular of the lens 2. through near F for convex or what would be through far F for concave (it won’t make it there), continues parallel to a perpendicular of the lens 3. Directly through the center of the lens and is unaffected. 3. Directly through the center of the lens and is unaffected.

5. Convex Lens (outside F) F F object Ray 1 Ray 2 Ray 3 Image forms here real and inverted p q

6. Convex Lens (inside F) F object Ray 1 Ray 2 Ray 3 F Image forms here virtual image upright and larger

7. Concave Lens F F Ray 1 Ray 2 must go though virtual F Ray 3 virtual lines Image forms here Virtual image upright and smaller