1. Optics

2. What is Optics?
the study of how light behaves, or
the collection and use of light to create images.
Optical system: Collects light and uses refraction and reflection to form an image
lenses-which refract (bend) light
mirrors - which reflect (bounce) light

3. How can it bend?
Light always travels in a straight line, but if it encounters another object or medium, it can change directions.
when light is bent so that it comes together it is called converging
when light is bent so that it spreads apart it is called diverging

4. Light Rays
an imaginary arrow that follows a single beam of light

5. Bending of light that occurs when light crosses a boundary between two different substances.

6. Objects or waves “bounce” off a surface

7. Images
A place where many light rays from the same point on an object meet together again in a point called the focus, or focal point.
They are “pictures” of objects
Two types of images:
virtual - "not real" - the image only seems to be where it is; cannot be projected onto a screen
real -can be projected onto a screen, because the light actually passes through the point where the image appears

8. Optical Devices Most optical devices have two functions:
1. They collect light rays
2. They bend the collected rays to form an image.
To illustrate how an optical device works, we draw ray diagrams to trace several light rays through a system

9. The Ray Diagram Two rules: 1. In through the focal point, out parallel
2. In parallel, out through the focal point.

10. Ray diagrams Help answer questions like:
Where is the focal point (or is there one)?
Will the image be magnified or reduced in size?
Will the image be upside down or right side up?
Will the image be inverted left or right?

12. Light rays bounce off a mirror at the same angle at which they arrive.
Law of Reflection
Light rays bounce off a mirror at the same angle at which they arrive.

13. Three Types of Mirrors plane - flat
image is right-side-up, the same size and virtual
concave - curved inward; creates a focal point
if the object is placed at the focal point, the image is inverted, smaller, and real
if the object is placed closer to the mirror the image is larger and virtual
convex - curved outward
the image is right-side-up, smaller, and virtual
objects appear farther away than they actually are

14. Lenses a transparent material that refracts light
usually made of glass or plastic with one or two curved surfaces

15. Bending of light that occurs when light crosses a boundary between two different substances.

16. Two types of lenses: convex converging
- thicker in the center than at the edges
converges the light rays (forms a focal point)
forms a real image (magnifies objects)
corrects farsightedness
concave diverging
thicker at the edges and thinner in the center
diverges the light rays
images are smaller and right-side-up
forms virtual images
corrects nearsightedness