Post on 28-Dec-2015
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Light
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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
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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)
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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
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Sources of light
Luminous object – gives off light
Illuminated object – reflects light
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Opaque materials do not allow light to pass through them; they only absorb and reflect light
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Transparent materials allow almost all light to pass through them; only a little light is absorbed and reflected
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Some light passes through translucent materials, but the image is distorted.
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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
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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
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Mixing colors
Pigment – colored material that absorbs some colors and reflects others
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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
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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
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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
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Light Pigment
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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.
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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
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Polarized light Light waves vibrate in only
one direction after passing through a polarizing filter