How do I see color?Photochemical receptors receive the light (____ and _____)

Rods-brightness

cones-the color

They release a ________ signal to the brain.

Brain interprets the signal

Primary colors of light: red, blue, green (mix together to make white.)

Optics and Reflection• Optics-the study of

how light behaves • Deals with the

collection and use of light to create images

• Includes: lenses, mirrors, and ______

• Law of __________: determines the reflected ray

• Light rays bounce off a mirror at the same angle at which they arrive

• We always define angles relative to the normal (the line perpendicular to the mirror (or lens)

Mirrors & Prisms

• Mirrors reflect light– Flat mirrors show

_______– Curved mirrors cause

light to come together or spread apart

• Prisms cause light to change directions– Traditionally used to

________ the colors of light and to show how light bends

Reflection & Mirrors• A mirror reflects rays of light so that they

change their path• ___________– the ray that comes from the

object and hits the mirror• ___________– the ray that bounces off the

mirror

Refraction and Lenses • A ____ uses __________ to cause light to

come together or spread apart• Refraction – The bending of light that

occurs when light crosses a boundary between two different substances– EX. Glass, Plastic, Water

• ____ – a shape of transparent material that is used to bend the light rays– Shape determines how much the light bends

Focal Point & Focal Length

• ___________– the point at which light rays meet after having entered a converging lens parallel to the principal axis.

• ____________- the distance from the center of the lens to the focal point

Where is the focal point in this eye diagram?

Where is the focal length?

Lens Types• Converging lenses – bend parallel light rays

passing through them inward ______ the focal point

• Diverging lenses – bend the parallel light rays passing through them outward ______ from the focal point

The Eye

• Lens, cornea, iris, retina optic nerve• Two convex lenses, refraction

Lens• The lens can change it’s shape to focus at different

distances.• A lens that focuses in front of the retina is a condition

called myopia (near sightedness)• A lens that focuses objects behind the retina is a

condition called hyperopia (far sightedness)

Long Focal Length

Short Focal Length

Use Diverging LensThicker on sides than in center

Use Converging LensThick in center than on the sides