1. What you should know about light!!

2. What is light? Light is a form of energy Light travels extremely fast
It carries energy and information
It travels in straight lines
It bounces and/or bends when it comes into contact with objects
Visible light has color
Light has different intensities (bright or dim)

3. How do we see most of the world?
Why do you see this slide?
Light from the projector is reflecting off the screen and going to your eyes.
What are some objects that you use that produce light and do not use reflected light?
Cell phones TV
Computer screen

4. How fast is it? Which is faster, the speed
of sound or the speed of light?
Light
Any guesses how much faster?
If you shine a flashlight at a mirror 170 meters away, it takes sec to go there and come back.
If you shout and it echo's back, it would take 1 full second
Light travels at about a million times faster than sound (light 86,000 mi/s and sound .21 mi/s)

5. Light can bounce and bend
Reflection
When it bounces off a surface
Refraction
When it moves from one medium
into another and bends
Pencil in water

6. Vision and Color White light – what is it? So, what is color?
Light composed of all the colors
So, what is color?
Color is how we perceive the energy of light.
Colors represent light of different energies
Red has the lowest energy
Violet has the highest energy

7. How we see color
On the surface of the retina, there are photoreceptors.
The cells release a chemical signal that travels along the optic nerve to the brain where it is translated into a perception of color
Two types of photoreceptors
Cones-3 types-They respond to the 3 primary colors (RGB)
Rods-respond to differences in intensity and not color.

8. How we see colors Additive colors
3 photoreceptors (cones) operate together
The color you see depends on the energy received by each type of cone cell.
When equal amounts of red and
green light reach your eyes, you see yellow
RGB is used for anything that
emits light
Additive colors

9. Subtractive colors
Chemicals, known as pigments, in the dyes and paints absorb some colors and reflect others
They work by taking away colors from white light
Magenta absorbs green and reflects red and blue
CMYK is used for anything that
reflects light