light waves sec 1. light waves strike objects reflected absorbed transmitted
TRANSCRIPT
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