Light Waves Sec 1 Light Waves Strike objects

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 rightside 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, lightsensitive 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 rightside 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