1. Color and Polarization
Light and Reflection
Color and Polarization

2. Colors Different wavelengths of visible light have different colors.
Objects have colors because they reflect certain wavelengths of light
We see the reflected color
When no light is reflected, objects appear black
When all wavelengths of light are reflected equally, objects appear white

3. Colors

4. Colors Colors may be added or subtracted to produce other colors
Additive primary colors: red, blue, green
Combining two if these colors produces one of the additive secondary colors: cyan, yellow, magenta
Combing all three additive primary colors produces white
Complementary color – the color of light needed to add to another color of light to produce white light

5. Colors

6. Colors Subtractive primary colors: yellow, cyan, magenta
Also called primary pigments
Combining two if these colors produces one of the subtractive secondary colors: red, blue, green
Combing all three subtractive primary colors produces black
Black is the absence of color

7. Colors

8. Polarization of Light
Linear polarization – the alignment of electromagnetic waves in such a way that the vibrations of the electric fields in each of the waves are parallel to each other
When the vibrations are in random directions the light is unpolarized
Typical light
To polarize light there needs to be some sort of filter
Transmission polarization – only light that can pass through the filter (polarizer) continues
The rest is either absorbed or reflected

9. Polarization of Light
Transmission axis – the axis that the filter lets light pass through
A polarizer can be used to determine if light is polarized and in what direction by rotating the polarizer
When the plane of polarization is parallel to the transmission axis the light is brightest
When the plane of polarization is perpendicular to the transmission axis, no light passes through

10. Polarization of Light

11. Polarization of Light
Light can also be polarized by reflection and absorption and scattering
Similar to transmission polarization with a reflecting or scattering surface acting as the polarizer

12. Polarization of Light