Physics- Color
What can any color be made?
Any color can be made from over-lapping 3 colors, not just RGB, although RGB produces the most colors.
Explain why the sky is blue
As sunlight goes through the air, it bumps into particles. Most of the light, like red and orange, pass through the molecules whit no problem, but blue, on the other hand, does not due to its high frequency, so it bounces all over the place because the particles scatter it when it hits them! That's why the sky gets blue.
Explain black
Black is NOT a color itself, but is the absence of light. (absorbs it all)
What color of white light does Bea absorb to cause her to reflect yellow?
Blue
Why are clouds white and bright?
Clouds are white because they are made up of a variety of differently shaped water droplets. They each scatter a range of frequencies from low to high. The result is a white cloud! The tiny droplets in clouds vibrate together, in step, which results in large amounts of energy. Hence, the cloud is bright!
How is color produced?
Color is produced by the frequencies of light emitted or reflected by things. We see yellow in Bea when light of a certain frequency reaches our eye.
Explain color printing
Color printing is done on a press that prints each page with 4 different color inks- MYC and black. The mixing of colors makes many colors.
Explain color television
Color television is made up of a bunch of tiny spots, each less than a millimeter across. When lit, these spots are red, green, and blue
Explain electrons being forced into vibration and when light is emitted and absorbed
Electrons can be forced into larger vibrations by the vibrations of electromagnetic waves (such as light). Like a tuning fork, electrons then send out their own energy waves in all directions. Different materials have different natural frequencies for absorbing and reemitting light. Electrons vibrate at certain frequencies; in other materials, they vibrate at different frequencies. At the resonant frequency, where the amplitudes of oscillation are large, light is ABSORBED. At frequencies below and above the resonant frequencies, light is REEMITTED.
Explain elements and their colors
Every element (hydrogen, oxygen, mercury, etc. think of periodic table) has its own color when made to emit light in the gaseous state. If the atoms are far enough apart that their vibrations are not interrupted by neighboring atoms, their true colors are emitted. Each element produces its own, unique set of lines because each element has its own distinct configuration of electrons, and these emit distinct frequencies of light when electrons change from one energy state to another in the atom (gas state, etc.)
What does it mean to say an object is opaque?
If an object is opaque, the light passes back into the medium in which it came. This is reflection.
In what case will an object be the same color as the light that shines on it?
If an object reflect light of all visible frequencies, like the white of this index card, it will be the same color as the light that shines on it.
If molecules in the sky scattered low-frequency light more than high-frequency light, how would the colors of the sky and sunsets appear?
If low frequencies were scattered more, red light would be scattered out of the sunlight on its long path through the atmosphere at sunset, and the sunlight to reach your eye would be predominantly blue and violet. So sunsets would appear blue!
Distant, dark mountains are bluish in color, what is the SOURCE of this blueness?
If you look at distant, dark mountains, very little light from them reaches you, and the blueness of the atmosphere between you and the mountains predominates. The blueness is of the low-altitude "sky" between you and the mountains. That's why distant mountains look blue!
Spectroscope
Instrument used to analyze the light from a glowing element. A spectroscope displays the spectra of light from hot gases to other light sources.
Explain Isaac Newton's experiment
Isaac Newton was the first to make a systematic study of color. He passed a ray through a prism. and it cast the sunlight into a patch of colors.
When green light shines on a red rose, why do the petals look black>
It absorbs all the green. The green contains NO red to be reflected, and the red contains NO range of colours in green to be reflected, so it absorbs them all-black
Explain an object that is red absorbing and reemitting light
Most objects absorb light of some frequencies and reflect the rest. If an object absorbs light of most visible frequencies (absorbs because the light's frequency matches electron's frequency), and reflects red, for example, the object appears red. (reflect because red falls below or above the electron's natural frequencies).
Is mixing paints and dyes similar to mixing light?
NO, mixing paints and dyes is VERY different than mixing colored light.
Explain mixing paints and dyes
Paints and dyes contain finely divided solid particles of pigment that produce their colors by absorbing light of certain frequencies and reflecting light of other frequencies. Pigment absorbs light of a WIDE range of frequencies and reflects a WIDE range as well. That's why you get poopy colors when you mix paint.
Spectra
Plural of spectrum
Color mixing by subtraction
Process of mixing paint colors
Additive primary colors
Red, Green, Blue. Produce highest number of different colors.
Why does sunlight appear yellow-green despite it producing white light?
Sunlight contains all colors and visible frequencies. The reason sunlight appears yellow-green is because of the BRIGHTNESS of the frequencies the sun produces. Light is the brightest of the frequencies, so we see yellow-green.
What should I think about when I look at the sky or objects?
THink about all those ultra-tiny optical tuning forks vibrating! (electrons)
What does the color of transparent objects depend on?
The color of a transparent object depends on the color it transmit, just like opaque object but with transmission.
What are the colors of most objects around me due to?
The colors of most objects around you are due to the way the objects reflect light.
What does the energy of absorbed light do to glass?
The energy of the absorbed light increases the kinetic energy of the atoms and the glass is warmed.
Radiation curve
The graphical distribution of brightness versus frequency of sunlight
When red light shines on a red rose, why do the leaves become warmer than the petals?
The leaves absorb rather tahn reflect the red light, so the leaves become warmer.
Pigment
The material in glass that selectively absorbs colored light. Electrons in pigment selectively absorb light of certain frequencies present in the light illuminating it.
Distant, snow-covered mountains reflect a lot of light and are bright. but they sometimes look yellowish, depending on how far away they are. Why are they yellow?
The reason that distant snow-covered mountains often appear a pale yellow is because the blue in the white light from the snowy mountains is scattered on its way to you. What happens to white when blue is scattered from it? The complementary color left is yellow
What are the reflected colors of objects?
The reflect colors of most objects are not pure, single-frequency colors, but are composed of a spread of frequencies. So, Bea, for example, may simply be a mixture of colours without blue and violet- or she could emit green light and red together (makes yellow).
Why is the sky less blue in areas?
The sky is less blue in areas because of particles which are larger are scattering lower frequencies compared to blue, particles like dust!
Why is the sky of the moon black?
The sky of the moon is black because there are no molecules in the air!
Line spectrum
The spectrum of an element which appears not as a continuous band of color, but as a serious of lines, each with a distinct frequency.
What's the difference between the light a tiny particle reflects compared to a bigger particle?
The tinier the particle in the sky, the higher the frequency of light will scatter.
How do objects appear under white light?
Under white light, white objects appear white, and colored objects appear in their individual color.
Explain why water is pale, greenish-blue
Water is transparent to nearly all visible frequencies of light. Water molecules absorb infrared waves because they resonate to the frequency of infrared waves. The energy of infrared waves is transformed in to kinetic energy of the water molecules. Infrared is a strong component of the sunlight that warms water. The frequency of visible light nearest infrared is red. Water molecules resonate SOMEWHAT to the visible-red frequencies. This causes a gradual absobtion of red light by water. When red is taken away from red light, what do you have? CYAN! The color of water is cyan, too: OMG!
Why do we see a DEEP BLUE of water?
We see a deep blue in water because it's reflecting the color of the sky. The ACTUAL color of the water is pale, greenish-blue.
Complementary colors
When 2 colors are added together to produce white, they are called complementary colors. EVERY color has some complementary color that when added will produce white. Whenever you subtract a color from white light, you end up with the complementary color.
Why is the sky red, orange, and magenta at sunset and dawn?
When light passes through the atmosphere, light of lower frequencies are transmitted while light of high frequencies are scattered. At morning and sunset, sunlight reach us through a longer path than at noon. The through the atmosphere is longer, so more blue is scattered from the sunlight. Less and less blue remains as it reaches lower parts of atmosphere. The sun appears progressively redder. The colors of the sky is consistent with our rules for color mixing. When blue is subtracted from white light, the complementary color left is yellow! The subtraction of violet leaves orange! The subtraction of green is magenta! The relative amounts of scattering depends on atmospheric conditions, which change day to day, giving us a variety of sunsets.
White light doesn't result JUST from combining all visible colors; what else can form white?
White not only results from the combination of all visible frequencies, it can also result from combining only red, green, and blue light of equal brightness
Color mixing by addition
process of mixing colored light
red + green = ANSWER; red + blue= ANSWER; blue + green = ANSWER
red + green = yellow; red+blue= magenta; blue + green= cyan
White= ANSWER + ANSWER; white= ANSWER + ANSWER; white= ANSWER + ANSWER
yellow + blue= white; magenta + green= white; cyan + red= white
Why does the sky appear blue to us, but not astronauts?
A faint color will show itself against a dark background (such as space), but not against a bright one. That's why you see such visible blue because it's against space, and astronauts don't see the blue sky at all.
Explain what the sky is like after a rainstorm
After a heavy rainstorm, the sky is a deep blue because all the large particles have been washed away.
What do all the color, one on top of the other, form?
All the colors, one on top of the other, combine to produce white light.
Sunlight
An example of white light
What range of frequencies can an object only reflect, transmit, or absorb?
An object can only reflect frequencies in the range of the light illuminating it. Bea look REALLY yellow beside the lamp because the light the lamp emits. The little colour an object has of that light illuminated REALLY comes out when lit with it.
What does it mean to say an object is transparent?
If an object is transparent, the reemitted light passes THROUGH it.
Subtractive primary colors
MYC: Magenta, yellow, cyan
When do objects appear black?
Objects appear black when they absorb light of ALL visible frequencies. Some objects that aren't black can appear black in certain situations. Stacked razor blades, for example, can appear black in areas because the light is just absorbed after being reflected by the shiny surface so much! Black objects do not absorb ALL the light that falls on them, for there is always some reflection at the surface. If there was not reflection, you wouldn't be able to see them at all!
Spectrum
Spread of colors going, in order, from red, orange, yellow, green, blue, and violet.
