reflect
objects must ___ light to be seen
opaque
materials do not allow light to pass through them, ONLY absorb and reflect light
translucent
some light passes through ___materials
transparent
materials that allow almost all light to pass through them and only a little light is absorbed and reflected
reflection of light
is when a light wave strikes and object and bounces off
law of reflection
the angle at which light strikes a surface is the same as the angle at which it is reflected
regular reflection
reflection of light waves from a smooth surface
diffuse reflection
reflection of light waves from a rough surface
refraction
change in the speed of a light wave when it passes from one material to another
index of refraction
indicates how much a material reduces the speed of light
greater
the more light is slowed the ___ the index of refraction
prism
a seperate white light into a visible spectrum based on light wavelengths
rainbow
caused by water droplets refracting wavelengths of sunlight
mirage
image from refraction of light through air layers of different densities
color
determined by wavelength of light an abject reflects
white
when objects reflect all colors of visible light
black
when objects absorb all colors of visible light
filter
transparent material that absorbs all colors except the color or colors it transmits
filters
can make objects appear to be different colors
retina
where light enters and focuses in the eye
cones and rods
two types of cells that absorb light in the retina
cones
distinguish colors and detailed shapes most effective in daytime
rods
sensitive to dim light most effective in nightime
color blindness
when 1 or more sets of cones do not function properly
pigment
colored material that absorbs some colors and feflects others
red,green and blue
primary colors of light
magenta, cyan and yellow
primary colors of pigment
additive colors
primary colors of light...combine to form white
subtractive colors
primary colors of pigment ....combine to form black the absence of reflected light
incondescent lights
hot tungsten wire glows. gives off light and heat
flourescent lights
electrons collide with gas atoms releasing ultraviolet radiation absorbed by phosphors lining the bulb; give off light and uses LESS energy and LAST LONGER
Neon light
tubes filled with gas that produce light from electron collisions; dif colors can be made by adding dif gases
sodium vapor lights
heated neon gas glows and wamth turns sodium into vapor, makes a yellow-orange glow and used for outdoor lighting
tungsten-halogen lights
have a filament and gas enclosed in a glass bulb to make intensly bright lights
lasers
light beam made when identical atoms sending off identical light waves;made from gas, liquid or solid
coherent lights
light made from a laser where waves of SAME wavelength are aligned and travel SAME direction
incoherent lights
light mae from a laser where waves of MULTIPLE wavelengths are NOT aligned and travel in MANY directions
industry, science, comunication, medicine, compact discs
5 areas lasers are used