Light 1 Visible Light Wavelengths range from 400

Light 1

Visible Light Wavelengths range from 400 nm to 700 nm n Longest wavelength = red n Shortest wavelength = violet n 1 nm = 1 x 10 -9 m n 2

Speed of Light does not require a medium n The speed of light depends on the medium n The more dense the material, the slower the light n Light travels fastest in a vacuum (no medium) n 3

Speed of Light Speed of light in a vacuum = 3. 00 x 108 m/s n Speed of light first calculated by Albert Michelson n The symbol, c, is used to represent the speed of light in a vacuum n 4

Sources of light n Luminous object – gives off light n Illuminated object – reflects light 5

n Opaque materials do not allow light to pass through them; they only absorb and reflect light 6

n Transparent materials allow almost all light to pass through them; only a little light is absorbed and reflected 7

n Some light passes through translucent materials, but the image is distorted. 8

Light and Colors – determined by wavelength(s) of light that an object reflects n Objects appear to be white when they reflect all colors of visible light n 9

Light and Color Objects appear to be black when they absorb, rather than reflect, all colors of visible light n Filter – transparent material that absorbs all colors except the color or colors it transmits n 10

Mixing colors n Pigment – colored material that absorbs some colors and reflects others 11

Colors (Light) Primary colors of light are additive colors – combine to form white n Primary colors of light – red, green, and blue n Secondary Colors of light magenta, cyan, and yellow n 12

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Pigments Primary colors of pigments are subtractive colors – combine to form black, the absence of reflected light n Primary colors of pigment – magenta, cyan, and yellow n Secondary colors - red, green, and blue n 14

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Complementary Colors n One primary color and one secondary color that, when mixed, produce white light n n (White light is the combination of all possible wavelengths of light) One primary pigment and one secondary pigment that, when mixed, produce black 16

Light Pigment 17

The eye Sclera – white part n Cornea – clear refractive surface n Iris – colored part of eye (controls how much light enters the eye) n Pupil – hole through which light passes n Optic nerve – bundle of nerves at the back of the eye relaying messages to the brain. n 18

n Retina – made up of two types of cells that absorb light Cones – distinguish colors and detailed shapes; most effective in daytime vision n Rods – sensitive to dim light; most effective in nighttime vision n 19

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Polarized light n Light waves vibrate in only one direction after passing through a polarizing filter 21