Chapter 12.3 Reflection and Color

Angle of Reflection = Angle of Incidence

Balls bouncing on a pool table follow laws of reflection.

Rough surfaces reflect light in many directions, called DIFFUSE REFLECTION

When the water is still, reflection is “ clearer ”

The image in the convex mirror (left) looks smaller. The images in the concave mirror (right) looks bigger.

How Objects React to light Objects can be classified into three categories  Opaque  Transparent  Translucent

Opaque Objects Do not allow light to pass through them Examples are brick, carpet, wood, apple, etc. Objects appear the color they are because of the color of light they reflect; all other colors are absorbed

Transparent Objects Allow light to pass through them Items are “see-through” Examples are glass and cellophane Objects appear the color they do based on the color/frequency of light they allow to pass through

Translucent Objects Allow some light to pass through but scatters most of the light within it Cannot see things clearly through a translucent object Examples are a block of wax or a frosted light bulb

R O Y G B I V Red Orange Yellow Green Blue Indigo Violet White light Triangular Prism

More on R O Y G B I V Why is the apple red? White light strikes the apple All colors absorbed except red Red light is reflected

Still More on R O Y G B I V What color is the apple now? Green light strikes the apple Green light is absorbed. No color is reflected so apple appears black

Additive RGB Colors Green Blue Red white Yellow Cyan Magenta

Adding colors of LIGHT

CMY-Subtractive Colors Magenta Cyan Yellow black red blue green

Pigments – they subtract specific colors of light, so you only see the colors that were not “subtracted”

Refraction, or bending of light as it moves from air to water

Angles are measured with respect to the line which is perpendicular to the interface. When light travels from one medium--such as air, to another one of higher density--such as water, usually the light ray bends toward the perpendicular line.

Total Internal Reflection, as in fiber optic cables.

The critical angle for diamond in air is 24.5 degrees; any ray which strikes the surface on the inside at an angle of greater than 24.5 degrees will not escape the diamond.

The Convex Lens as a Magnifier