This document discusses the nature of light as an electromagnetic wave, how light interacts with different materials as either luminous or illuminated bodies, the characteristics of light like wavelength and speed, and concepts such as luminous flux, illuminance, luminous intensity, the additive and subtractive properties of light, and how dyes and pigments produce color. It also covers topics ranging from the primary and complementary colors of light and pigments to polarized light and thin film interference.
2. Light
We see objects because light is either
emitted or reflected by the object
3. 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 EE 8 m/s
10. Transparent
Transmits light
without distortion
Ex: crystal clear water
11. Translucent
Transmits light but the
image is distorted
Ex: lampshade
12. Opaque
Transmits no light
All light is absorbed or
reflected
Ex: brick
13. White Light
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
14. Mixing Light Colors
Red and Green = Yellow
Blue and Green = Cyan
Red and Blue = Magenta
16. 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 reflects others, but they
are larger and mix to form suspensions.
17. Dyes and Pigments
The absorption process of light forms colors by
the subtractive process
18. Primary Pigments
Absorb one color from white light and reflect 2 colors
Yellow absorbs Blue Reflects red and Green
Magenta absorbs Reflects Blue and Red
Green
Reflects Blue and Green
Cyan absorbs Red
19. Secondary Pigments
Absorb 2 colors from white light and reflect one color
Red absorbs Green Reflects Red
and Blue (Cyan)
Green absorbs Red Reflects Green
and Blue (Magenta)
Reflects Blue
Blue absorbs Red
and Green (yellow)
20. Complementary 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
21. What color would a yellow banana
appear if it is hit with green light?
Answer:
Green, yellow can reflect red and green,
but there is only green light hitting it.
22. What color would a yellow banana
appear if it is hit with blue light?
Answer:
Black, the yellow absorbs blue light so
there is no light to reflect
23. What color would a yellow banana
appear if it is hit with cyan light?
Answer:
Green, the yellow absorbs blue light
Cyan – Blue = Green
24. Polarized Light
Light that only
vibrates in one plane.
Polarized light will
only pass through a
polarized filter if it is
parallel to the
vibrating light
25. Thin Film Interference
The beautiful colors
are caused when light
reflects off of 2
surfaces
Example: Oil and
water or the 2 layers
of a bubble