2 Visible Light Wavelengths range from 400 nm to 700 nm Longest wavelength = red Shortest wavelength = violet 1 nm = 1 x 10 -9 m
3 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)
4 Speed of Light Speed of light in a vacuum = 3.00 x 10 8 m/s Speed of light first calculated by Albert Michelson The symbol, c, is used to represent the speed of light in a vacuum
5 Sources of light Luminous object – gives off light Illuminated object – reflects light
6 Opaque materials do not allow light to pass through them; they only absorb and reflect light
7 Transparent materials allow almost all light to pass through them; only a little light is absorbed and reflected
8 Some light passes through translucent materials, but the image is distorted.
9 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
10 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
11 Mixing colors Pigment – colored material that absorbs some colors and reflects others
12 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
14 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
16 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
18 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.
19 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