Light, Color, and Polarization Unit 13: Light and Optics Light, Color, and Polarization

Color Intro What are the primary colors of light? List the colors of the rainbow in order What do all the colors of the rainbow add up to?

Section 3: Visible Light and Colors Characteristics “White” light is a combination of red, orange, yellow, green, cyan, blue, and violet A prism can separate these colors out By refraction of different wavelengths of color

Visible Light 700 nm 400 nm Red orange yellow green cyan blue violet Longest Wavelength Lowest Frequency Least Energy Violet: Shortest Wavelength Highest Frequency Most Energy

Primary Colors Red Blue Green Blue Red Green

Secondary Colors: Mixture of 2 Primary Colors Magenta (Blue and Red) Cyan (Blue and Green) Yellow (Red and Green) A mixture of all three primary colors produces white light Blue Red Magenta Blue Blue Green Cyan Blue Red Red Yellow White Green Green

Blue Red Green Since secondary colors are a mix of two primaries: Mixing primary and secondary colors produces white light White Light = Primary Color + Secondary Color White Light = Blue + Yellow White Light = Green + Magenta White Light = Red + Cyan Blue Red Green

Primary colors of light Primary pigments (ink) Red Blue Green Magenta Cyan Yellow

Primary pigments (ink) adds up to black Primary colors (light) Red Blue Green Primary pigments (ink) Magenta Yellow Cyan are secondary pigments Primary colors add up to white light Red Magenta Yellow Blue Green Cyan are secondary colors Primary pigments (ink) adds up to black Yellow Green Red Cyan Blue Magenta

Intro Index of Refraction The principles of Refraction, Reflection, Diffraction are similarly applied to sound and light waves. Review: Reflection: light bounces off reflective surfaces Ex: looking a mirror or reflection in water Diffraction: bend of light around a barrier Ex: a dim corner of a dark room when light comes through an open door Refraction: light bends as passes from one media to another. Is determined by Snell’s Law Ex straw looks like it is bent in a glass of water

Rainbows are produced by the refraction of light

Thin Films Light from one side of a bubble cancels out light from the other side showing color from white light

Diffraction and Refraction and not the same! Diffraction Grating can be used to disperse light into colors like a prism A prism used refraction to disperse light Diffraction gradients use the interference of light to produce colors

Diffraction and Polarization Clip

Polarization of Light Light is an electromagnetic wave These waves produce an electric field at a right angle to the magnetic field Usually the rays are unpolarized which means they are oscillating in random directions.

Polarized Light Some crystals can cause unpolarized light to pass through and produce polarized light which has its electromagnetic fields aligned in the same direction. Transmission axis- line along which light is polarized

Transmission axis- line along which light is polarized Light at 90º to the transmission axis cannot pass through.

How polarized sunglasses work Glare When light reflects off the ground (a horizontal surface) it is polarized horizontally. Sunglasses stop glare They are polarized vertically so that horizontal glare cannot get through