Light and Reflection

1. 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