Question 1

Plants appear green to us because they ____.
A)absorb green wavelengths
B)reflect blue wavelengths
C)reflect green wavelengths
D)absorb all visible wavelengths
E)reflect all visible wavelengths

Accepted Answer

Plants appear green because they reflect green wavelengths of light. The chlorophyll in plants absorbs most of the other colors in the light spectrum but reflects green, which is why they appear green to us.

Question 2

When the atmosphere becomes loaded with particles, only the ____ red wavelengths are able to penetrate the atmosphere, and we see a ____ Sun.
A)longest; red
B)shortest; red
C)longest; blue
D)shortest; white
E)longest; yellow

Accepted Answer

The longest wavelengths, which are in the red part of the spectrum, are able to penetrate the atmosphere when it is loaded with particles, leading to the appearance of a red Sun.

Question 3

The blue color of the sky is a result of ____.
A)selective scattering of visible light by air molecules
B)the filtering effect of water vapor in Earth's atmosphere
C)reflection of sunlight off Earth's oceans
D)transmission of visible light through the ozone layer in Earth's stratosphere
E)absorption of short wavelengths by air molecules

Accepted Answer

The blue color of the sky is primarily due to the selective scattering of visible light by air molecules, a phenomenon known as Rayleigh scattering. This process scatters shorter wavelengths of light (blue and violet) more than longer wavelengths. However, our eyes are more sensitive to blue light, which is why we perceive the sky as blue.

Question 4

What color would the sky be if air molecules selectively scattered only the longest wavelengths of visible light?
A)White
B)Blue
C)Red
D)Black
E)Violet

Accepted Answer

The sky would appear red because the longest wavelengths of visible light are at the red end of the spectrum. If air molecules selectively scattered only these wavelengths, red light would dominate the sky's color.

Question 5

When we look at a cloud, it appears white because countless cloud droplets ____.
A)absorb all wavelengths of visible sunlight
B)reflect all wavelengths of visible sunlight into space
C)scatter all wavelengths of visible sunlight away from Earth
D)scatter all wavelengths of visible sunlight toward Earth
E)scatter all wavelengths of visible sunlight in all directions

Accepted Answer

Cloud droplets scatter all wavelengths of visible sunlight in all directions. This scattering by numerous tiny droplets gives clouds their white appearance, as all colors of the visible light spectrum are scattered equally.

Question 6

A star that is cooler than our Sun appears ____.
A)more violet
B)redder
C)brighter
D)whiter
E)bluer

Accepted Answer

Stars that are cooler than our Sun emit light that is more towards the red part of the spectrum, making them appear redder. This is due to Wien's displacement law, which states that the peak wavelength of radiation emitted by a star shifts to longer wavelengths (towards the red part of the spectrum) as the temperature decreases.

Question 7

When electromagnetic waves from the Sun reach the human eye, they stimulate antenna-like nerve endings in the ____.
A)iris
B)retina
C)pupil
D)cornea
E)sclera

Accepted Answer

The retina contains photoreceptor cells (rods and cones) that are sensitive to light. When electromagnetic waves from the Sun reach these cells, they are stimulated, leading to the perception of light and color.

Question 8

Haze can scatter light from the rising or setting Sun in a way that produces bright light beams, called ____, radiating across the sky.
A)anticrepuscular rays
B)crepuscular rays
C)blue haze
D)sun dogs
E)glories

Accepted Answer

Crepuscular rays are the bright beams of light that can appear when the Sun is low on the horizon, such as during sunrise or sunset, and its light is scattered by particles in the atmosphere.

Question 9

If Earth did not have an atmosphere, the sky would appear ____ during the day.
A)white
B)black
C)red
D)blue
E)violet

Accepted Answer

Without an atmosphere, there would be no scattering of sunlight, which means the sky would appear black during the day, similar to how it looks from space.

Question 10

A star much hotter than our Sun radiates more energy at ____.
A)shorter wavelengths and appears redder
B)shorter wavelengths and appears bluer
C)longer wavelengths and appears redder
D)longer wavelengths and appears bluer
E)about the same wavelengths and appears whiter

Accepted Answer

Stars that are much hotter than our Sun emit more energy at shorter wavelengths, which corresponds to the blue end of the spectrum, making them appear bluer.

Question 11

If the setting Sun appears red, you may conclude that ____.
A)the Sun's surface temperature has cooled somewhat at the end of the day
B)the longest wavelengths of visible light are striking your eyes
C)the next day's weather will be stormy
D)you will not be able to see the Moon that night
E)the shortest wavelengths of visible light are striking your eyes

Accepted Answer

The red appearance of the setting Sun is due to the scattering of shorter wavelengths of light (blue and violet) by the atmosphere, leaving the longer wavelengths (red) to reach the observer's eyes. This phenomenon is explained by Rayleigh scattering.

Question 12

White light is perceived when ____ strike(s)the cones of the eye with nearly equal intensity.
A)a single long wavelength
B)a single short wavelength
C)all visible wavelengths
D)all short wavelengths
E)all long wavelengths

Accepted Answer

White light is perceived when all visible wavelengths strike the cones of the eye with nearly equal intensity. This is because white light contains all the colors of the spectrum, and when they are combined in equal measure, the perception is that of white light.

Question 13

The blue color of distant mountains is due primarily to ____.
A)diffraction of light
B)scattering of light
C)refraction of light
D)emission of light
E)absorption of light

Accepted Answer

The blue color of distant mountains is primarily due to the scattering of light, specifically Rayleigh scattering, which causes shorter (blue) wavelengths of light to scatter more than longer wavelengths as they pass through the Earth's atmosphere.

Question 14

The sky will begin to turn milky white ____.
A)when the concentration of ozone begins to reach dangerous levels
B)when small particles such as dust and salt become suspended in the air
C)when the relative humidity decreases below about 10 percent
D)on an oppressively hot day of the year
E)when an inferior mirage occurs

Accepted Answer

The sky can appear milky white when small particles like dust and salt are suspended in the air, scattering sunlight and giving the sky a whitish appearance. This phenomenon is related to the scattering of light by aerosols and particulate matter in the atmosphere.

Question 15

Red sunsets, blue moons, and milky-white skies are mainly the result of ____.
A)refraction
B)dispersion
C)reflection
D)scattering
E)diffraction

Accepted Answer

Scattering is the primary reason for the color variations in the sky, including red sunsets, blue moons, and milky-white skies. This phenomenon occurs when molecules and small particles in the atmosphere scatter sunlight in different directions. The scattering of shorter wavelengths (blue and violet light) by atmospheric gases causes the sky to appear blue during the day. During sunrise and sunset, the light path through the atmosphere is longer, so more of the shorter wavelengths are scattered out, leaving the longer wavelengths (reds and oranges) to dominate the sky's color.

Question 16

Which type of particle causes a whitish haze, and a glare in clouds near the Sun?
A)Aerosols
B)Cloud droplets
C)Air molecules
D)Water molecules
E)Nitrous oxide

Accepted Answer

Aerosols are responsible for causing a whitish haze and glare in clouds near the Sun due to their ability to scatter and absorb sunlight.

Question 17

Imagine that a piece of paper is illuminated with white light and appears red. You see red light because the paper ____.
A)absorbs red and reflects other visible wavelengths
B)emits red light
C)reflects red and absorbs other visible wavelengths
D)disperses white light
E)transmits red light

Accepted Answer

The paper appears red because it reflects red light and absorbs other visible wavelengths. This is why we perceive the color of objects based on the wavelengths of light they reflect rather than absorb.

Question 18

Some people will remark that the "Sun appears to be drawing up water" when they are actually observing ____.
A)brocken bow
B)anticrepuscular rays
C)crepuscular rays
D)glories
E)halos

Accepted Answer

The answer of Some people will remark that the "Sun...

Question 19

The sky is blue because air molecules selectively ____ blue light.
A)scatter
B)absorb
C)diffract
D)disperse
E)emit

Accepted Answer

The sky appears blue because air molecules scatter shorter wavelengths of light, like blue, more than they scatter other colors.

Question 20

Another name for diffuse light is ____.
A)scattered light
B)refracted light
C)dispersion of light
D)transmitted light
E)diffracted light

Accepted Answer

Scattered light is another term for diffuse light, which describes light that has been scattered in many directions, often by particles or irregularities in the medium through which it is passing, resulting in a soft, non-directional light.

Quiz 20: Light, Color and Atmospheric Optics

Plants appear green to us because they ____.

When the atmosphere becomes loaded with particles, only the red wavelengths are able to penetrate the atmosphere, and we see a Sun.

The blue color of the sky is a result of ____.

What color would the sky be if air molecules selectively scattered only the longest wavelengths of visible light?

When we look at a cloud, it appears white because countless cloud droplets ____.

A star that is cooler than our Sun appears ____.

When electromagnetic waves from the Sun reach the human eye, they stimulate antenna-like nerve endings in the ____.

Haze can scatter light from the rising or setting Sun in a way that produces bright light beams, called ____, radiating across the sky.

If Earth did not have an atmosphere, the sky would appear ____ during the day.

A star much hotter than our Sun radiates more energy at ____.

If the setting Sun appears red, you may conclude that ____.

White light is perceived when ____ strike(s) the cones of the eye with nearly equal intensity.

The blue color of distant mountains is due primarily to ____.

The sky will begin to turn milky white ____.

Red sunsets, blue moons, and milky-white skies are mainly the result of ____.

Which type of particle causes a whitish haze, and a glare in clouds near the Sun?

Imagine that a piece of paper is illuminated with white light and appears red. You see red light because the paper ____.

Some people will remark that the "Sun appears to be drawing up water" when they are actually observing ____.

The sky is blue because air molecules selectively ____ blue light.

Another name for diffuse light is ____.