Transcript Light - Weebly

Light
Section 1 The Behavior of Light
A. Light and matter—objects must reflect light
to be seen.
1. Opaque materials do not allow light to pass
through them; they only absorb and reflect light.
2. Some light passes through translucent
materials.
3. Transparent materials allow almost all light
to pass through them; only a little light is
absorbed and reflected.
Light
B. Reflection of light—a light wave strikes an
object and bounces off.
1. Law of reflection—the angle at which light
strikes a surface is the same as the angle at
which it is reflected.
2. Regular reflection—reflection of light waves
from a smooth surface
3. Diffuse reflection—reflection of light waves
from a rough surface
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How Light Is Reflected
Light
C. Refraction of light—change in the speed of a
light wave when it passes from one material to
another
1. Index of refraction—indicates how much a
material reduces the speed of light; the more light is
slowed, the greater the index of refraction.
2. Prisms—separate white light into visible
spectrum based on light wavelengths
3. Rainbows—caused by water droplets refracting
wavelengths of sunlight
4. Refraction of light through air layers of different
densities can result in a(n) mirage.
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DISCUSSION QUESTION:
Why can’t you see an object in the dark?
Light
Section 2 Light and Color
A. Colors—determined by wavelength of light an
object reflects
1. Objects appear to be white because they reflect
all colors of visible light.
2. Objects appear to be black because they absorb,
rather than reflect, all colors of visible light.
3. Filter—transparent material that absorbs all
colors except the color or colors it transmits
4. Filters can make objects appear to be different
colors.
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C. Mixing colors
1. Pigment—colored material that absorbs
some colors and reflects others
2. Primary colors of light—red, green, and blue
3. Primary colors of pigment—magenta, cyan,
and yellow
4. Primary colors of light are additive colors
combine to form white
5. Primary colors of pigments are subtractive
colors—combine to form black, the absence of
reflected light
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Section 4 Using Light
A. Polarized light—light waves vibrate in only
one direction after passing through a polarizing
filter
Behavior of Light
When light interacts with matter, some light can be
absorbed, some can be transmitted, and some can be
reflected.
When light waves are reflected, they obey the law of
reflection  the angle of incidence equals the angle of
reflection.
Light waves are refracted, or bent, when a light wave
changes speed as it travels from one material to another.
Light and Color
You see color when light is reflected off objects and into
your eyes.
Red, blue, and green are the three primary colors of light
and can be mixed to form all other colors.
The color of a pigment is due to the wavelengths of the
light reflected from the pigment. The primary pigment
colors are magenta, cyan, and yellow.