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Discover the fascinating world of light, from its diverse wavelengths and speed to how it interacts with objects, creates colors, and is perceived by the human eye.
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Visible Light • Wavelengths range from 400 nm to 700 nm • Longest wavelength = red • Shortest wavelength = violet • 1 nm = 1 x 10-9 m
Speed of Light • Light does not require a medium • The speed of light depends on the medium • The more dense the material, the slower the light • Light travels fastest in a vacuum (no medium)
Speed of Light • Speed of light in a vacuum = 3.00 x 108 m/s • Speed of light first calculated by Albert Michelson • The symbol, c, is used to represent the speed of light in a vacuum
Sources of light • Luminous object – gives off light • Illuminated object – reflects light
Opaque materials do not allow light to pass through them; they only absorb and reflect light
Transparent materials allow almost all light to pass through them; only a little light is absorbed and reflected
Some light passes through translucent materials, but the image is distorted.
Light and Color • Colors – determined by wavelength(s) of light that an object reflects • Objects appear to be white when they reflect all colors of visible light
Light and Color • Objects appear to be black when they absorb, rather than reflect, all colors of visible light • Filter – transparent material that absorbs all colors except the color or colors it transmits
Mixing colors • Pigment – colored material that absorbs some colors and reflects others
Colors (Light) • Primary colors of light are additive colors – combine to form white • Primary colors of light – red, green, and blue • Secondary Colors of light - magenta, cyan, and yellow
Pigments • Primary colors of pigments are subtractive colors – combine to form black, the absence of reflected light • Primary colors of pigment – magenta, cyan, and yellow • Secondary colors - red, green, and blue
Complementary Colors • One primary color and one secondary color that, when mixed, produce white light • (White light is the combination of all possible wavelengths of light) • One primary pigment and one secondary pigment that, when mixed, produce black
Pigment Light
The eye • Sclera – white part • Cornea – clear refractive surface • Iris – colored part of eye (controls how much light enters the eye) • Pupil – hole through which light passes • Optic nerve – bundle of nerves at the back of the eye relaying messages to the brain.
Retina – made up of two types of cells that absorb light • Cones – distinguish colors and detailed shapes; most effective in daytime vision • Rods – sensitive to dim light; most effective in nighttime vision
Polarized light • Light waves vibrate in only one direction after passing through a polarizing filter