Light Waves Sec 1

Light Waves Strike objects Reflected Absorbed Transmitted

Properties of objects Opaque Transparent Translucent

Opaque A material that reflects or absorbs all of the light that strikes it.

Transparent Material transmits light Light passes through allowing you to see what is on the other side

Translucent Some light passes through Material scatters light as the light passes through You cannot see details

Reflection Two kinds of wave reflection Regular and Diffused

Regular Reflection Occurs when parallel rays of light hit a smooth surface All the rays are reflected at the same angel

Diffuse Reflection When parallel rays of light hit a bumpy, or uneven surface The rays are reflected at different angels

Mirrors Sheet of glass Smooth, silver-colored coating When light passes through the mirror, the back coating causes the light to reflect regularly, allowing you to see an image

Image Is a copy of an object formed by reflected or refracted rays of light

Plane Mirror Flat mirror Produces a image that is right-side up and The same size as the object being reflected

Virtual Image The image you see when you look in a plane mirror is a virtual image Right-side up or upright

Concave Mirrors Surface curves inward Can form virtual images, real images, or no image Depends on position of the object in relation to the focal point

Real Image Formed when rays actually meet at a point The images are upside down, or inverted

Focal Point The point at which the rays meet

Convex Mirrors A mirror with a surface that curves outward Images are always virtual

Refraction and Lenses Sec 2

Index of refraction measure of how much a ray of light bends when it enters that material

Mirages Is an image of a distant object caused by refraction of light Page 245

Concave lens Is thinner in the center than at the edges

Convex lenses Is thicker in the center than at the edges

Color Sec 3

Color The color of an object is the color of light it reflects White=reflects all colors Black= absorbs all colors

Primary Colors Three colors that can be used to make any other color Red, green, and blue Any two primary combined in equal amounts produce a secondary color

Seeing Light Waves Sec 4

The Eye Organ System Each part plays an important part in helping you see

Cornea Light enter the eye through this transparent surface The cornea protects the eye It also acts as a lens bending light waves as they enter the eye

Iris Is a ring of muscle that contracts and expands This changes the amount of light that enter the eye Also give the eye color

Pupil Looks black As light dims, the pupil enlarges allowing in more light Vis versa

Lens Behind the pupil Refracts light, forming and image Page 257

Retina Layer of cells lining the inside of the eye Contains many of tiny, light-sensitive cells called, rods and cones

Rods Rods contain pigments that react to small amounts of light Important for seeing at night

Cones Respond to color Three types: red, blue, and green Function with bright

Optic Nerve The signals generated by the rods and cones travel to the brain along a short, thick nerve The brain turns the image right-side up

Correcting Vision Lenses in glasses are either concave or convex The type of lens used depends on whether the eye is too long or too short

Nearsightedness Person can see nearby things clearly, but objects at a distance appear blurry Eyeball is a little to long Concave lens correct this

Farsightedness Person can see far away, but objects nearby appear blurry Eyeball is too short This is corrected with convex lenses