Wave Behavior - Reflection  the bouncing back of a wave after it strikes a barrier.  All waves, sound, light, water, EMS, etc., can be reflected!!  examples: mirror, water wave bouncing back from a pool wall, echo Reflection

Wave Behavior –Reflection Cont   Plane mirrors and other smooth surfaces reflect light to form clear images. Incidence Ray Angle of Incidence Angle of Reflection Plane Mirrors = Reflected Ray

Wave Behavior   the bending of waves caused by a change in their speed as they pass from one medium to another.   More dense the medium, slower the wave Refraction

Wave Behavior   Greater the change in speed – more the wave bends.   Ex. light going from air through a convex lens can make images appear larger as the light waves bend.  examples: items in glasses of water, lenses, eyeglasses, telescope, microscope Refraction

Refraction with devices   Triangular shaped glass or acrylic that separate white light into its different colors by refracting light waves. Prism

Wave Behavior  the spreading out of waves through an opening or around the edge of an obstacle.  examples: water waves around dock or pier, water waves around rock outcrop, sound through a door to a room Diffraction

Refraction with devices  Thin piece of material that bends light waves around microscopic slits, creating a rainbow. Diffraction Grating

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Wave Behavior  Absorption --- this occurs  Absorption --- this occurs when the energy is not transferred through, or reflected by the given medium. The energy enters the medium and does not exit.   Objects or substances that absorb any wavelength of electromagnetic radiation become warmer and convert the absorbed energy to infrared radiation.

Wave Behavior   Transmission of waves occurs when waves pass through a given point or medium. Sound waves are transmitted through solids, liquids, and gases. Light waves can travel through some materials but not others.

Interaction of Light Waves with Materials TransparentTranslucent  Most of the light passes through these materials. Examples: Air, water, clear glass. Uses: light bulbs, clock faces, window glass   These materials will transmit some light, but cause it to be scattered so no clear image is seen. Objects viewed through translucent materials can be seen, but not clearly. Examples: frosted windows, notebook paper.

Opaque  No light passes through these materials.  The materials will either reflect light, absorb light, or both.  Examples: wood, mirrors, metal, fabric, etc. Interaction of Light Waves with Materials

Creating a View on the World 1.Position your index card in a horizontal position. Draw a line across the top 3 cm from the top and across the bottom 3 cm from the bottom. 2.Create three, 3 cm x 3 cm boxes along the drawn lines on the card. 3.Place a piece of transparent, translucent and opaque material across the opening. 4. Label each box with the type of material marker. transparent translucentopaque

Why Humans See the Color We See ColorWhiteBlack  Is determined by the wavelength being absorbed or reflected.  An object will appear to be a certain color because it is reflecting that color. Example: A shirt that is red is reflecting the red wavelength but absorbing all others.  Reflects all colors in visible light.  Absorbs all colors in visible light.

Why we see color Colored Filters   allow only certain colors of light to pass/transmit through them; they absorb or reflect all other colors. Ex. a blue filter only transmits blue light. Objects seen through a blue filter will look blue if the objects reflect blue; objects of other colors will appear black because the other color wavelengths are being absorbed by the filter. Let’s experiment with filters:   mer/java/primarycolors/colorfilte rs/index.html mer/java/primarycolors/colorfilte rs/index.html