1. Notes 23.3: Lenses and Images

2. Ray Diagrams for Pinholes:
Object- real physical thing that gives off or reflects light
Pinhole and Screen
Light ray – straight line arrow that represents a single “beam” of light. (need 2 rays)
Image – “picture” of the object that is formed where the rays land on the screen

3. Two types of Images:
Virtual Image- image is perceived by the brain and eye as being some place that the light does not come from. Ex: image in a plane mirror is behind the mirror
Real image – images are formed where the light rays actually come together; can be projected on a screen. Ex: pinhole, camera

4. Two Types of Lenses:
1. Converging lens – bends the light rays together so they meet at a single point.
Ex: magnifying glass
Also called convex, they are thicker in the middle than at the edges

5. Focal point – the point where parallel light meets when in travels through a lens.
Focal Length – distance from center of the lens to the focal point. (measured in cm, m)

6. 2. Diverging lens – bends light outward away from the optic axis.
Ex: Some eye glasses
Also called a concave lens, it is thinner in the middle than at the edges.

7. Ray diagrams for lenses will have:
An object
At least two light rays (we will draw three)
Optic axis – imaginary line going through the center of the lens
Two focal points on each side of the lens.
An image (may be real or virtual)