Wave Interactions Wave Interaction w When a wave

Wave Interactions ØWave Interaction w When a wave meets an object or another wave. w When a wave passes into another medium w Examples: reflection, diffraction, refraction

A. Reflection Normal ØReflection w when a wave strikes an object and bounces off incident beam reflected beam

A. Reflection ØWhen a wave bounces off a surface that is cannot pass through

B. Refraction ØRefraction w bending of waves when passing from one medium to another w caused by a change in speed • slower (more dense) light bends toward the normal • faster (less dense) light bends away from the normal SLOWER FASTER

B. Refraction ØThe bending of a wave as it enters a new medium at an angle.

B. Refraction ØRefraction depends on… w speed of light in the medium w wavelength of the light - shorter wavelengths (blue) bend more

B. Refraction ØExample: View explanation.

C. Diffraction ØThe bending of a wave as it moves around an obstacle or passes through a narrow opening.

C. Diffraction ØDiffraction w bending of waves around a barrier w longer wavelengths (red) bend more opposite of refraction

Light II. Light and Color Ø Light and Matter Ø Seeing Colors Ø Mixing Colors

A. Light and Matter ØOpaque w absorbs or reflects all light ØTransparent w allows light to pass through completely ØTranslucent w allows some light to pass through

B. Seeing Colors ØWhite light w contains all visible colors - ROY G. BIV ØIn white light, an object… w reflects the color you see w absorbs all other colors REFLECTS ALL COLORS ABSORBS ALL COLORS

B. Seeing Colors ØThe retina contains… w Rods - dim light, black & white w Cones - color

B. Seeing Colors ØColor Blindness w one or more sets of cones does not function properly Test for red-green color blindness.

C. Mixing Colors ØPrimary light colors w red, green, blue w additive colors w combine to form white light w EX: computer RGBs View Java Applet on primary light colors.

C. Mixing Colors ØFilter w transparent material that absorbs all light colors except the filter color View Java Applet on filters.

C. Mixing Colors ØPigment w colored material that absorbs and reflects different colors ØPrimary pigment colors w cyan, magenta, yellow w subtractive colors w combine to form black w EX: color ink cartridges

C. Mixing Colors Light Pigment When mixing pigments, the color of the mixture is the color of light that both pigments reflect.