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Physics chapter 28
chapter 28
Question | Answer |
---|---|
What is color caused by? | caused by the frequencies of light that are given off or reflected by an object |
where is color blindness of defective cones result? | in the retina of the eye. |
who was the first person to really explore color in detail? | Isaac Newton |
what did he do? | passed a beam of sunlight through a glass prism |
what did issac see? | white light separate into a series of different colors |
what is a spectrum? | a ranfe |
what is the color spectrum? | a range of color |
What are the colors in the color spectrum? | red, orange, yellow, green, blue, violet |
What is white light a combination of? | all colors of light |
What is an example of white light? | sunlight |
white light is not truly a combination of all colors. who figured this out? | newton |
is black a color? | no it is the absence of any of the colors of light |
how is the color of an object determined? | by the frequencies of light that are reflected back from the object |
Can all frequencies be reflected? | no some frequencies of light may be absorbed |
what do all materials have? | a natural frequency |
when does resonance occur? | if the natural frequency matches any of the frequencies of light. and the frequency will remain |
for what materials will re-emitted light continue through? | transparent |
for opaque material what happens? | re-emitted light is reflected back |
What do most materials do? | will absorb some frequencies and reflect some |
why is the type of light source important? | because an object can reflect only light of frequencies present in the light source |
what are the different kind of light sources? | candlelight, incandescent, fluorescent |
For transparent what does the object depend on? | the light that is transmitted |
what is a pigment | the material which absorbs particular colors of light |
What is sunlight? | a combination of all frequencies of visible light. |
what else is sunlight? | a combination of all the colors of the spectrum |
red+blue= | magenta |
blue+green= | cyan |
green+red= | yellow |
green+red+blue= | white |
what are additive primary colors? | three colors that when added together make white |
What do TV screens use? | additive colors |
what happens when the TV is on? | the spots are lit red, blue, or green |
What are complementary colors? | two colors that when added together form white |
how can only two colors do this? | one of the two colors must be a combination of two additive primary colors |
What are examples of the two colors? | 1. yellow+blue= white 2. magenta+green=white 3. cyan+red=white |
where are complimentary colors on the color wheel | opposite of each other |
when using complimentary colors is it possible to determine what light color would be seen if particular colors were removed from white light? | YES |
when mixing paint is it different than mixing light? | yes |
when mixing red green and blue light what does the color become? | white |
when mixing red and green and blue paint what do the colors become | brown |
what does paint and dyes contain? | pigments |
how do paints and dyes get their color? | by color mixing by subtraction |
how does light get its color? | by color mixing by addition |
what are the subtractive primary colors? | magenta, cyan, and yellow |
what are subtractive primary colors used for? | printing |
what is scattering? | is a process in which sound or light is absorbed and reemitted in all directions |
how is light scattered? | by molecules and larger specks of matter that are far apart from one another in the atmosphere |
what happens when the particle size is smaller? | the higher the frequency is scattered. |
what is the order of the colors that are scattered the most? | violet, blue, green, yellow, orange, and red |
when there are a lot of particles larger than oxygen and nitrogen molecules what happens to the frequency? | the lower the frequencies of light are scattered more |
what happens when there are no molecules? | the sky is black |
what makes up clouds? | water droplets in a variety of sizes |
The different-size droplets of water molecules result in a variety of frequencies for scattered light: | 1. low frequencies from larger droplets 2. high frequencies form tinier droplets |
what is the overall result? | a white cloud |
what do larger particles scatter? | lower frequencies |
what is the atmosphere nearer the earth made up of? | larger particles |
what are the lower frequencies? | red |
At sunrise and sunset how does light travel? | longer path through the atmosphere |
Why is water greenish blue? | because water molecules absorb red |
what is the true color of ocean water? | cyan |
why is the froth in the wave white? | because its droplets of many sizes scatter many color frequencies |
why does the water look sometimes deep blue? | it is a reflection of the color of the sky |
what is water transparent to? | all frequencies of light |
what does water absorb? | infrared frequencies |
how is water warmed? | by sunlight |
what do water molecules resonate to? | visible red frequencies |
what does every element have? | has its own characteristic color when it emits light |
what is the color a blend of? | various frequencies of light |
when is light of each frequency emitted? | when the electrons change energy states |
do electrons have well-defined energy levels? | yes the lower energy near the atomic nucleus and higher energy father from the nucleus |
what happens when an atom absorbs external energy? | one or more of its electrons is boosted to a higher energylevel |
what state is an energized atom in? | excited state |
what is an excited state? | a state with greater energy than the atom's lowest energy state |
how long does the excited state last for? | it is only momentary, for the electron is quickly drawn back to its original or a lower level of energy |
what is a photon? | a pulse of light |
what do the different electron orbits in an atom look like? | steps in energy levels |
what happens when an electron is raised to a higher level? | the atom is excited |
what happens when the electron returns to its original level? | it releases energy in the form of light |
what is a spectroscope? | an instrument that analyzes light from glowing elements |
what did Newton's spectroscope use? | two lenses a thin slit, and a prism to produce a clear spectrum from white light |
what does an incandescent bulb have? | a continuous spectrum |
what three elements have a different line spectrum? | hydrogen, sodium, and mercury |
who can use the line spectra and what for? | chemists can use the line spectra for identifying an element just as a fingerprint can be used to identify a person |
how can the atomic composition of the sun and distant galaxies be determined? | by examining the line spectra. |