Colors, Dyes and Pigments

Light Waves

Light

● We see objects because light is either

emitted or reflected by the object

Light

● Light is an electromagnetic wave that the human

eye can detect

● Light has wavelengths that range from 400 nm

(violet) to 700 nm (red)

● The speed of light is 3 E 8 m/s

Equations

● c = λ f

● c = speed of light (3 E 8 m/s)

● λ = wavelength

● f = frequency

​Distance = velocity x time
D= vt

Luminous Body

● A luminous body

emits light waves

● Ex: the sun

Illuminated Body

● An illuminated body

reflects light waves

● Ex: the moon

Luminous Flux (P)

● Luminous Flux is the rate at which light is

emitted from a source

● It is measured in lumen (lm)

Illuminance (E)

● Illuminance is the amount of light that is

reflected

● E = P
4πd²

● Units are lm/m2 or lux (lx)

● E = illuminance

● P = luminous flux

● d = distance

Transparent

● Transparent materials

transmit light without
distortion

● Ex: crystal clear water

Translucent

● Translucent materials

transmits light but the
image is distorted

● Ex: lampshade

Opaque

● Opaque materials

transmit no light

● All light is absorbed or reflected.

● Ex: brick

White Light

● White light is produced by adding the colors red,

blue and green

● This is called the additive process

● Red, blue and green are called the primary light

colors

Mixing Light Colors

● Red and Green =

● Blue and Green =

● Red and Blue =

● Yellow

● Cyan

● Magenta

Complementary Light Colors

● Yellow and Blue

● Cyan and Red

● Magenta and Green

ALL Produce white light

​Why? Because all of these combinations result in red, blue, and green being mixed together.

Dyes and Pigments

● Dyes are molecules that dissolve in liquids

to form colored solutions. They absorb certain wavelengths and reflect others.

● A pigment also absorbs certain wavelengths

and reflect others, but they
are larger and mix to form suspensions.

Dyes and Pigments

● The absorption process of light forms colors by

the subtractive process

Primary Pigments

Absorb one color from white light and reflect 2 colors

● Yellow absorbs Blue

● Magenta absorbs

Green

● Cyan absorbs Red

● Reflects red and Green

● Reflects Blue and Red

● Reflects Blue and Green

​If a color is absorbed, we WON'T see it!
Only reflected colors will be seen.

Secondary Pigments

Absorb 2 colors from white light and reflect one color

● Red absorbs Green

and Blue (Cyan)

● Green absorbs Red

and Blue (Magenta)

● Blue absorbs Red and

Green (yellow)

● Reflects Red

● Reflects Green

● Reflects Blue

Complementary Pigments

● Complimentary pigments produce black

light

● Black is not a color just the absence of

light

● No light is being reflected

● Note: The primary light colors are the

secondary pigments and vice versa

Great Job! You made it to the end.

Later this week I will go over any questions you might have and continue the notes in person with you. See you soon.
-Coach Bush