PHS 208 Weeks 5-8
Color perceived in retina by 3 sets of cones:
Pigment R, Pigment G, Pigment B
The colors produced by passing through a prism are arranged in what order?
Red Orange Yellow Blue Indigo Violet (Roy G. Biv)
The electron Volt (eV) is the energy gained by an electron that moves across a positive voltage of _ volts
1.0 volts
Orange light of 620 nanometers has an energy of 1. 1 eV 2. 1.5 eV 3. 2 eV
2 eV
Visible light is made of photons in energy range around _ eV
2-3 eV
Visible light is composed of photons in the energy range of around
2-3 electron volts
Radiations shorter than _ nm can't be sensed by eye
400
The visible spectrum lies in the middle range with wavelengths between _ nm for blue and _ nm for red
400, 700
How much nanometers is violet light?
410 nanometers
The energy levels in mercury produce a strong green line at 1. 700 nanometers 2. 625 nanometers 3. 546 nanometers
546 nanometers
How much nanometers is red light?
680 nanometers
Light with wavelength longer than _ nm is invisible
700
What is the chromaticity curve?
A color triangle w/ 3 primary colors at each corner.
In light emission, if the electrons have well-defined energy levels, you observe 1. line spectra 2. a narrow spectrum 3. a broad spectrum
a narrow spectrum
What is complementary colors?
a pair of colors which can produce white passing through the white point (W)
Energy-photons create what?
a pulsating electromagnetic disturbance
What are phosphors?
absorb UV light and produce visible light
A red object appears "red" to the eye when illuminated with white light. Light from other colors is not seen by the eye because those colors are _
absorbed
A single wavelength light beam incident on a thin film can have the reflected beam either reinforced diminished depending on 1. angle of incidence 2. film thickness 3. all of the above 4. neither of the above
all of the above
If the thickness of oil on water exceeds about 0.5 micron (5/10,000 of a millimeter) the interference effects of white light will 1. become very pronounced and bright 2. become negligible, making the surface appear dark 3. all overlap, making the surface appear white or colorless
all overlap, making the surface appear white or colorless
Objects can absorb all colors except the colors of their _, which are reflected
appearance
Lower energies (longer wavelengths) _ detected by human eye. They can be detected by special _ sensors
are not, infrared
An unpolarized beam of light can be represented by two vector components of wave oscillations oriented 1. 180 degrees from each other 2. at right angles to each other 3. parallel to each other
at right angles to each other
Different portions of the sun's energy are absorbed in the _, _, and _.
atmosphere, water, glass
If the raindrops were made of a material whose refractive index was independent of wavelength (n = constant), the rainbow would: 1. be white 2. not change 3. be even more colorful
be white
When a pure blue object is illuminated with red light, the object appears 1. white 2. black 3. blue 4. red
black
If red (instead of blue) light was preferentially scattered, the sunsets would appear _
blue
The sunsets appear red because of preferential scattering of _
blue
Human daylight vision is most effective in the _ (550 nm) where the sun's energy spectrum is in the region of its maximum
blue-green
The conservation of angular momentum in light emission applies to 1. infrared radiation 2. x-rays 3. both of the above 4. neither
both of the above
Fluorescent tubes have an energy spectrum with a _ spectrum, and a series of _ and _ peaks in the red, blue, and green
broad, sharp and intense
If you change the gas in a neon light, you would 1. use a different spectrometer 2. change the color 3. increase the voltage
change the color
Light rays are made of photons where the energy ranges from a _
color
Our perception of color comes from the _ _ _ which enter the eye
composition of light
The order of colors is _
constant
What is Saturation/Chroma?
how much the hue dominates
What is a nanometer?
A unit of distance that is too small to be resolved
What is electron volt (eV)?
A unit of energy where energy gained by an electron that moves across a positive voltage of 1 volt
There are 3 receptors in the eye that respond to different wavelengths:
Blue-violet, orange-red, green
How is color produced?
Color is produced by the absorption of selected wavelengths of light by an object
What was the effect of the pair of glass slides pressed close together? 1. it created fringes in the glass 2. nothing happened
it created fringes in the glass
What is incandescent light?
light produced by temperature of object
If two polarizers have their orientation axes aligned parallel the first will absorb half the unpolarized light and the second will transmit 1. half the remainder of unpolarized light 2. one-quarter the remainder of unpolarized light 3. linearly polarized light
linearly polarized light
Infrared and radio waves are the _ wavelength side
long
As we move through the visible spectrum of violet, blue, green, yellow, orange and red, the wavelengths become _
longer
Light from the sun transmitted through a prism can be adjusted to give a spectrum of colors that consists of 1. red and green 2. red and blue 3. many colors from red to blue
many colors from red to blue
The ultraviolet portion of the sun's spectrum 1. penetrates 1000m of water 2. is not blocked by glass 3. both of the above 4. neither of the above
neither of the above
What is flux?
number of photons passing through a unit area in a unit time
The foam on a colored liquid is white because 1. of scattering at the many liquid-air interfaces 2. of dilution of the liquid 3. the selective absorption by the liquid
of scattering at the many liquid-air interfaces
The energy levels in the electron transition leading to light emission differ by 1. one unit of angular momentum 2. two units of angular momentum 3. one unit of linearly polarized light
one unit of angular momentum
Light going from lower refractive index air to high refractive index glass has a phase change in the reflected beam of 1. one-half wavelength 2. one wavelength 3. all of the above 4. neither of the above
one-half wavelength
Who discovered that light can be split into a prism?
Isaac Newton
Ultraviolet (UV), x-rays, and gamma rays are on _ wavelength side
short
What did you see when you pressed your fingers nearly close together? 1. two fingers close together 2. small lines in the space between the fingers 3. nothing
small lines in the space between the fingers
The wavelengths of visible light are _ than common objects
smaller
In a rainbow, each color emerges at different angles: red light emerges at 42 degrees, blue light at a _ angle
smaller (40 degrees)
For every color signal or flux of photons reaching the eye, _ ratio of response within the three types of cones is triggered. It is this ratio that permits the perception of a particular color
some
Which of the following is NOT a part of the electromagnetic spectrum? 1. radio waves 2. infrared radiation 3. X-rays 4. sound waves 5. gamma rays
sound waves
Higher energies (shorter wavelengths) can be seen by what?
special devices
With electric discharge in gases, light can be produced in a 1. broad spectrum 2. spectrum with sharp lines 3. intermediate spectrum
spectrum with sharp lines
In the electromagnetic spectrum, as the radiation changes from x-rays to visible light, the velocity: 1. increases 2. decreases 3. stays the same
stays the same
If you increase the intensity of a light source you increase 1. the amount of light emitted 2. the wavelength of light 3. the characteristic color of the light
the amount of light emitted
What is electromagnetic radiation?
the complete range of energies of electromagnetic waves from the lowest to the highest (from largest to smallest wavelengths), including, in order, radio, infared, visible light, ultraviolet, X-ray, and gamma ray waves.
The sensation of color depends on what?
the composition of light, which is a mixture of white light and colored light
Light can be emitted when electrons make the transition between two states. The photon energy is equal to 1. the sum of the energies of the two levels 2. the energy of the lower level 3. the difference of energy between the two levels
the difference of energy between the two levels
In infrared light, compared to ultraviolet light 1. electron transitions are not involved 2. the energies are higher 3. the energies are lower
the energies are lower
What is composition of light?
the energy spectrum of photons
What happened when you looked at a light source through both polarizers that were oriented perpendicular to each other? 1. nothing 2. the polarizers dimmed the light a little bit 3. the polarizers dimmed the light significantly 4. the polarizers were black where they crossed
the polarizers were black where they crossed
If we observe a rainbow when sunlight shines on rain, why don't we see a complete rainbow circle? 1. we are too far away from the rainbow 2. the reflection angle limits the arc length 3. we are too high off the ground
the reflection angle limits the arc length
What is dominant wavelength?
the single wavelength that is perceived by the human eye
Thomas Young described thin film colors due to light scattered from 1. pigments 2. top and bottom sides 3. air pores in the film
top and bottom sides
Light from sun is absorbed by earth's atmosphere in the _ and _ but some reaches the earth
ultraviolet, infrared
In thin-film interference colors, the colors change with 1. viewing angle of the observer 2. distance to the observer 3. temperature of the observer
viewing angle of the observer
What color is the shortest wavelength
violet
The eye responds to wavelengths in ONLY in _ light in the electromagnetic spectrum
visible
The receptors of the eye respond to light in the _ spectrum
visible
The sun's spectrum encompasses the _ spectrum
visible
Fluorescent lamps have mercury vapor which emits uv radiation. The tube is coated with phosphors which produce _
visible light
The light emitted by the sun falls within the _ region and extends beyond the red (into the infrared, IR) and the _ with a maximum intensity in the yellow
visible, ultraviolet (UV)
If we specify a _ in the visible range, we can attribute a color to it
wavelength
Light is electromagnetic waves with color identified by its _
wavelength
The signature of color is the _ of light
wavelength
The colored light may have a dominant _ or _
wavelength, hue
The preferential scattering of blue light causes the sky to be blue and the sunsets red. If the scattering by air molecules anddust was independent of wavelength (no preferential scattering) the color of the sky would be _
white
Rods explain what in dim light?
why we perceive colored objects as shades of grey
Is light reflected off the floor or a table polarized? 1. yes 2. no 3. I couldn't tell
yes
What does the signature of color tell us?
It identifies the color's location in the spectrum
What are cones?
Allow us to see different colors
What are rods?
Effective in dim light and sense differences in light intensity.
The intensity/brightness of light is defined by the what?
Flux
Can all colors be produced by mixing lights of the 3 primary colors?
NO
If a slightly curved convex lens is placed on a plane glass surface a series of colored circles are seen in reflected light. These are known as 1. Newton's Rings 2. Tyndall's Rings 3. Rayleigh's Rings
Newton's Rings
Does human vision distinguishes between polarized light and unpolarized light?
No
What are the 2 types of photosensitive cells?
Rods, cones
How do we represent all colors?
The chromaticity curve
As we move through the visible spectrum, what happens to the wavelengths?
The wavelengths become longer
Are all the colors of soap bubbles due to interference effects?
Yes
Yes or no: White light can be produced by two colors.
Yes
What is a hue?
a color or shade
When looking at a bright incandescent light bulb (household bulb) what kind of a spectrum did you see through your spectrometer? 1. a continuous spectrum (like a rainbow) 2. a continuous spectrum with some bright lines superimposed 3. just bright lines on a dark background
a continuous spectrum (like a rainbow)
When looking at a bright incandescent light bulb (household bulb) what kind of a spectrum did you see through your spectrometer? 1. a continuous spectrum (like a rainbow) 2. a continuous spectrum with some bright lines superimposed 3. just bright lines on a dark background
a continuous spectrum (like a rainbow)
When looking at a fluorescent bulb what kind of spectrum did you see through your spectrometer? 1. a continuous spectrum (like a rainbow) 2. a continuous spectrum with some bright lines superimposed 3. just bright lines on a dark background
a continuous spectrum with some bright lines superimposed
When looking at a fluorescent bulb what kind of spectrum did you see through your spectrometer? 1. a continuous spectrum (like a rainbow) 2. a continuous spectrum with some bright lines superimposed 3. just bright lines on a dark background
a continuous spectrum with some bright lines superimposed
Fluorescent lamps operate by what?
a gas dischargr
As energy of light increases, wavelength _
decreases
The saturation _ as the hue is deleted with white lite
decreases
The life of a light beam: it is created, it travels through space and it is 1. reemitted 2. red-shifted 3. destroyed
destroyed
A prism refracts and _
disperses
James Clerk Maxwell showed that light was a form of _ _
electromagnetic radiation
Electrons are bound to the atom with fixed 1. mass 2. energies 3. spin
energies
When light is emitted from an atom: 1. energy is conserved 2. mass is conserved 3. color is conserved
energy is conserved
True reflection of light from thin film exhibits various colors dependent on 1. film thickness 2. density 3. both
film thickness
Circularly polarized light reflected at the Brewster angle from a flat sheet of glass will be 1. fully polarized 2. partially polarized 3. absorbed
fully polarized
Fluorescent tubes are coated with what?
phosphors
Rods do NOT perceive what? What do they perceive instead?
photon energy. The flux of incident photons
Retina has _ cells that contain pigments to absorb visible light
photosensitive
The colors of an object depend on three factors: a) interference, b)preferential scattering of short waves, and c) 1. pigment absorption 2. out-of-phase waves 3. density variations
pigment absorption
Isaac Newton discovered that light could be split into many colors by a _
prism
The color _ can't be represented by a single wavelength of light since it's a mixture of light in the red and violet regions
purple
Which of the following colors could not be represented by a single wavelength of light? 1. blue 2. indigo 3. violet 4. purple
purple
What color is the longest wavelength?
red
When you make your own rainbow with a sprinkler or light reflected off a bottle, what is the outer color?
red
If you project colored lights on all walls using flashlights and a filter, you can obtain yellow with 1. red and green lights 2. red and blue lights 3. green and blue lights
red and green lights
What colors are used in a T.V. color monitor?
red, green, and blue
In the Blue Sky Activity, What color was the light coming out if you were staring directly at the flashlight through the glass?
red-ish or yellow
A rainbow not only refracts and disperses light it also 1. reflects 2. absorbs 3. transmits
reflects
The rainbow is produced by sunlight reflecting from raindrops. The raindrops also are: 1. scattering 2. absorbing 3. refracting and dispersing
refracting and dispersing
The amount of reflect light incident on two transparent materials depends on differences in: 1. refractive indices 2. density 3. atomic weight
refractive indices
