Chapter 12.3 Reflection and Color Angle of Reflection = Angle of Incidence

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, calledDIFFUSE 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

BlueRed

white

YellowCyan

Magenta

http://home.att.net/~B-P.TRUSCIO/COLOR.htm

Adding colors of LIGHT

CMY-Subtractive Colors

Magenta

CyanYellow

black

redblue

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 withrespect to the line which isperpendicular to theinterface.

When light travels from one medium--such as air, toanother one of higherdensity--such as water,usually the light ray bendstoward the perpendicularline.

Total Internal Reflection, as in fiber optic cables.

The critical angle for diamondin air is 24.5 degrees; any raywhich strikes the surface on theinside at an angle of greaterthan 24.5 degrees will notescape the diamond.

The Convex Lens       as a Magnifier