Transcript Light Waves
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