25 terms

# Light and its Properties

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law of conservation of energy
energy can be neither created nor destroyed, but it can be converted from one form to another
light
a form of energy
light waves
electromagnetic radiation, energy traveling through space
amplitude
(a) maximum vertical displacement
wavelength
the distance between any two adjacent identical points of the wave
frequency
the number of wavelengths passing a fixed point in one unit of time, usually a second (Hz)
speed of light
c=3.00x10^8m/s
relationship between energy of light and frequency
the higher the frequency, the higher the energy; the lower the frequency, the lower the energy
visible region
400nm-700nm
refraction
the bending of light as it passes from one medium to another
why does refraction occur
the speed of light is affected by the density of the medium; light travels slower in the denser medium. As light passes into the denser medium, it bends toward the normal. On exiting to the less dense medium, it bends away from the normal, so the incident beam and the transmitted beam are parallel.
results of the refraction of light
rainbows, mirages, and the "twinkling" of stars
refractive index
the ratio of the speed of light in air to the speed of light in some other medium
dispersion
the separation of white light into its component colors
specular reflection
light reflected from a smooth surface. The observed beam appears to be reflected in one direction only giving the surface a shiny appearance
diffuse reflection
light reflected from a rough surface. Light is scattered in many directions, giving the surface a dull appearance. The angle of incidence must still equal the angle of reflection, but the rough surface creates many normals to the surface.
absorption
A colored object absorbs all wavelengths except those corresponding to the color it appears. Light of that color is reflected.
blue, green, and red are the additive primaries for transmitted light.
subtractive mixing
results from the removal of certain wavelengths of reflected light by absorption.
subtractive mixing process
start with white light, use blue, red, and green filters to remove particular wavelengths.
subtractive mixing primaries
cyan, magenta, and yellow
hue
wavelength classification; distinguishes one color from another (red, blue, yellow)
saturation
the extent to which white (or black or gray) is mixed with a pure hue; sometimes called purity
brightness
darkness or lightness of the color
achromatic
white, gray, black (no hue)