1. Seeing light When light from an object enters your eye, the eye sends a signal to your brain and you see the object. When light from an object enters your eye, the eye sends a signal to your brain and you see the object.

2. The Eye The sclera is “the white of the eye” The sclera is “the white of the eye” 6 tiny muscles connected to it control the eye’s movement 6 tiny muscles connected to it control the eye’s movement The cornea is the transparent coating which covers the iris and pupil. The cornea is the transparent coating which covers the iris and pupil. Light enters the eye through the pupil. Light enters the eye through the pupil. The pupil looks black from the outside The pupil looks black from the outside The size of the pupil is controlled by the iris- when it is bright the pupil is small, when it is dark, the pupil grows bigger The size of the pupil is controlled by the iris- when it is bright the pupil is small, when it is dark, the pupil grows bigger The iris is a ring of muscles which open and close the pupil in bright and dim light conditions. The iris is a ring of muscles which open and close the pupil in bright and dim light conditions. The iris is the colored part of the eye The iris is the colored part of the eye

3. The Eye After light passes through the iris, it enters the lens which with the help of the cornea refracts the light and forms an upside down image on the retina. After light passes through the iris, it enters the lens which with the help of the cornea refracts the light and forms an upside down image on the retina. The retina contains millions of photoreceptors (sensors which convert light into electric impulses which are sent along the optic nerve to the brain). The retina contains millions of photoreceptors (sensors which convert light into electric impulses which are sent along the optic nerve to the brain). There are two types of photoreceptors: There are two types of photoreceptors: Rods which allow us to see in low light Rods which allow us to see in low light Cones which allow us to see color and work best in brighter light Cones which allow us to see color and work best in brighter light The optic nerve sends signals representing color, light and dark from the eye to the brain which then interprets what we see. The optic nerve sends signals representing color, light and dark from the eye to the brain which then interprets what we see.

4. How it works! Light reflected off objects travels in a straight line into the eye through the cornea and the pupil. The light travels through the lens, which focuses it on the back of the eye, projecting an upside-down image onto the retina. Photoreceptors in the retina translate the image into electrical impulses, which travel along the optic nerve and into the brain. The brain makes sense of the signals and tells us what we see!

5. Nearsightedness When someone is nearsighted, their eyeball is too long (“egg shaped”). When someone is nearsighted, their eyeball is too long (“egg shaped”). They have problems seeing things far away They have problems seeing things far away The result is the focal point of an image is in front of the retina. The result is the focal point of an image is in front of the retina.

6. Farsightedness When someone is farsighted, their eyeball is too narrow. They have problems seeing things close up The result is an image which is behind the eye. Glasses correct vision by moving the image either forward or back until the image is on the retina. Lasers can be used to repair eyes in surgery

7. Primary Colors of Light: red, blue, green Primary Colors of Light: red, blue, green Primary Pigment Colors: magenta, cyan, yellow Primary Pigment Colors: magenta, cyan, yellow When all the primary colors are mixed together, you see white light! When all the primary colors are mixed together, you see white light! Let’s Experiment!!! Let’s Experiment!!! Additive Color Process