Deck 16: Light Waves and Color

Question 1

The primary difference between infrared and visible light is that

A) infrared travels faster than visible light.
B) they have different wavelengths.
C) infrared does not have a magnetic field associated with its electric field.
D) no materials currently known have the ability to reflect infrared.
E) they have different amplitudes.

Answer 1

they have different wavelengths.

Question 2

In Young's double-slit experiment, light was first passed through a narrow single slit before going on to the double-slits. The reason for the first slit was

A) to screen out all wavelengths except those in the visible light spectrum.
B) to reduce the brightness of the light so the interference pattern could be seen.
C) to polarize the light.
D) to ensure a constant phase relationship between the interfering light waves.

Answer 2

to ensure a constant phase relationship between the interfering light waves.

Question 3

Electromagnetic waves that travel through a vacuum are not

A) longitudinal waves.
B) transverse waves.
C) able to propagate, since there is no atmosphere.
D) oscillating.

Answer 3

longitudinal waves.

Question 4

The daytime sky is blue, on sunny days, because the atmosphere

A) is most efficient at scattering red light.
B) absorbs blue light.
C) contains small amounts of water vapor that give the air its blue color.
D) is more efficient at scattering blue light.
E) absorbs the red light.

Question 5

EM waves tend to be scattered the most by an object that is

A) magnetic.
B) a liquid.
C) reflective.
D) conducting.
E) about the same size as the wave.

Question 6

Which of the following colors has the shortest wavelength?

A) Orange
B) Yellow
C) Green
D) Red

Question 7

The evening sunsets are reddish orange because the atmosphere

A) absorbs blue light.
B) is more efficient at scattering blue light.
C) absorbs the red light.
D) contains small amounts of red dust that give the air its red color.
E) is most efficient at scattering red light.

Question 8

Which of the following is not an electromagnetic wave?

A) Light
B) Sound
C) Microwaves
D) Infrared
E) X-ray

Question 9

The normal human eye can detect colors whose wavelengths range from 380 nm to about

A) 550 nm.
B) 600 nm.
C) 650 nm.
D) 700 nm.

Question 10

Which statement is true?

A) Speed of light in air is lower than in glass.
B) Radio waves in the AM band are not electromagnetic waves.
C) Some electromagnetic waves will pass through walls that light cannot penetrate.
D) In air light travels much faster than radiation from a microwave oven.
E) Electromagnetic waves can't travel in perfect vacuum.

Question 11

Which two primary colors of light can be added to produce yellow?

A) Green and magenta
B) Red and green
C) Blue and green
D) Red and blue
E) Pink and mauve

Question 12

The frequency of blue light is ______ that of green light.

A) greater than
B) less than
C) the same as
D) greater than, the same as, or less than, depending on a source of light

Question 13

What primary color must be added to magenta light to produce white light?

A) Red
B) Yellow
C) Blue
D) Magenta
E) Green

Question 14

If the only light present is yellow, what color will a blue sweater appear to be?

A) Black
B) White
C) Blue
D) Yellow
E) Green

Question 15

When you look at a white light through a blue piece of glass, you observe blue light. This means that the blue glass

A) absorbs all of the blue light.
B) reflects all of the blue light.
C) transmits only the blue light.
D) transmits all colors except blue.
E) transmits only cyan and magenta.

Question 16

For visible light, which property of visible electromagnetic waves changes with color?

A) Wavelength
B) Amplitude
C) Frequency
D) Amplitude and frequency
E) Frequency and wavelength

Question 17

The light from an incandescent bulb is composed of

A) only red, green, and blue light.
B) only red, yellow, and turquoise.
C) only red and blue.
D) all wavelengths in the visible portion of the electromagnetic spectrum.
E) None of the choices is correct.

Question 18

The frequency of red light is ______ that of a green light.

A) greater than
B) less than
C) the same as
D) greater than, the same as, or less than, depending on a source of light

Question 19

When ultraviolet light reflects from a violet surface, we see

A) red.
B) violet.
C) white.
D) black.

Question 20

If a surface is illuminated by magenta light and the red is absorbed, then the color of the surface will appear as

A) blue.
B) red.
C) yellow.
D) green.

Question 21

The correct value for the speed of light in air is

A) 3 $\times$ 10⁵ km/h.
B) 3 $\times$ 10⁸ m/s.
C) 3.0 $\times$ 10⁵ m/s.
D) 1.86 $\times$ 10⁵ miles/h.
E) 1.86 $\times$ 10⁵ feet/s.

Question 22

Which of the following waves exhibit interference?

A) Sound, water, and light
B) Only sound
C) Only water
D) Only light
E) None of the choices.

Question 23

Two light waves combine and produce a region of darkness. Which of the following must be true in that region?

A) The waves were unpolarized.
B) The waves came from the same source.
C) The waves had different wavelengths.
D) The waves were a half-wavelength out of phase.

Question 24

A thin layer of oil floats on a water puddle. An observer sees a colored pattern. This happens because

A) two surfaces each transmit some light and reflect some light.
B) oil always does this, even if it is not on water.
C) water transmits light and never reflects light.
D) sunlight's frequency range shifts to infrared at the boundary of water and oil.

Question 25

When diffraction of light occurs with a single slit,

A) the interference fringes have the same brightness as the central bright spot.
B) a number of interference fringes are produced around the central bright spot.
C) a central bright spot with one dimmer spot on each side can be seen.
D) only one interference fringe can be seen.

Question 26

A beam of "unpolarized" light

A) does not have any polarized waves.
B) contains a single light wave with a fixed polarization direction.
C) can be polarized by reflecting it from a flat surface.
D) has a polarization direction that is constantly rotating.

Question 27

One common way to polarize a beam of light is to

A) filter out the longest wavelengths of the spectrum.
B) filter out the shortest wavelengths of the spectrum.
C) slow it down using a piece of glass.
D) use a sheet of Polaroid material.

Question 28

The polarization of a light wave is determined by the direction

A) of the oscillating electric field.
B) of the light's velocity.
C) of the fluorescent tube used as a light source.
D) perpendicular to both the electric and magnetic fields.

Question 29

When a beam of light passes through a narrow slit we can observe some light in the "geometrical" shadow of the slit. This light arrived by the process of

A) interference.
B) reflection.
C) refraction.
D) diffraction.

Question 30

A common property of all waves is the relationship between the speed (v), the wavelength ( $\lambda$ ), and the frequency of the wave (f). The correct equation for this relationship is which of the following?

A) " $\lambda$ = vf"
B) "f = v $\lambda$ "
C) "v = f/ $\lambda$ "
D) "v = f $\lambda$ "

Question 31

The leaves of an oak tree are green and those leaves use light to help the tree grow. If the tree were exposed only to green light

A) it would grow more quickly because green light is used by the tree.
B) the growth rate of the tree would not change.
C) it would not grow well because the tree does not use much green light compared to other wavelengths.
D) the growth rate would depend on how hot the green light was.

Question 32

The diffraction of light by the iris of the eye limits

A) the color response of our eyes.
B) the ability of our eyes to resolve very fine details.
C) our peripheral vision.
D) our ability to see in the dark.

Question 33

Under the correct conditions, two light waves can produce regions of reinforcement and regions of cancellation. This phenomenon is known as

A) interference.
B) reflection.
C) polarization.
D) refraction.

Question 34

A beam of orange light illuminates two slits that are closely spaced. The resulting intensity pattern is a series of bright and dark fringes. What happens to the intensity pattern if we now change to blue light?

A) The series of bright and dark fringes changes to circular fringes.
B) The series of bright and dark fringes spreads out.
C) The series of bright and dark fringes gets closer together.
D) The series of bright and dark fringes disappears.
E) Nothing changes.

Question 35

A piece of ordinary glass transmits about 92% of the visible light incident on the glass. The transmittance of the glass can be increased by

A) increasing the intensity of the incident light.
B) applying an anti-reflective coating to both sides of the glass.
C) slightly tilting the glass with respect to the light beam.
D) making the glass thicker.

Question 36

Polaroid sunglasses are designed to transmit primarily

A) light other than blue.
B) horizontally polarized light.
C) vertically polarized light.
D) refracted waves.
E) longitudinal light waves.

Question 37

A common use of a diffraction grating is to

A) split light into different polarizations.
B) focus light onto the retina.
C) separate light into its separate wavelengths.
D) reflect light into a different direction.

Question 38

If a person has a shiny nose, applying powder will remove the shine without reducing the amount of light reflecting from the nose. This is an example of

A) polarization.
B) diffraction.
C) specular reflection.
D) diffuse reflection.

Question 39

When you see your shadow on a sunny day, it has a fuzzy edge. This is

A) not caused by diffraction because the wavelength of visible light is too small to produce visible diffraction around a person.
B) not caused by diffraction because diffraction only occurs for openings, not objects blocking light.
C) an example of diffraction.
D) not caused by diffraction because there are too many wavelengths in sunlight to see the effect.

Question 40

A property of electromagnetic waves that makes them different than other kinds of waves such as sound or water waves is that

A) they are transverse waves.
B) they do not require a medium.
C) their speed can change when moving in different media.
D) they have many possible wavelengths.

Question 41

Prisms and diffraction gratings can both

A) invert a light ray's frequency and wavelength
B) change sunlight into a single color.
C) slow down light to a few meters per second, if used back-to-back.
D) break the incoming light beam into its constituent colors.

Question 42

Infrared waves have a ___________ wavelength than microwaves.

Question 43

Which of the following types of radiation diffracts most when it passes through a diffraction grating?

A) Blue
B) Violet
C) Yellow
D) Red

Question 44

An unpolarized beam of light of a single pure color can be split apart into two separate beams by using

A) a birefringent material like calcite.
B) the human retina.
C) metal-ceramic inversion.
D) a thin layer of oil.
Fill in the Blank Questions

Question 45

When unpolarized light passes through a polarizing filter,

A) all the light passes through and remains unpolarized.
B) all the light passes though and is now polarized.
C) it is completely absorbed by the filter.
D) about half the light passes through and remains unpolarized.
E) about half the light passes through and is now polarized.

Question 46

Ultraviolet light has ________ wavelength and __________ frequency relative to visible light.

A) longer; larger
B) longer; smaller
C) shorter; larger
D) shorter; smaller

Question 47

Radio waves have ________ wavelength and __________ frequency relative to visible light.

A) longer; larger
B) longer; smaller
C) shorter; larger
D) shorter; smaller

Question 48

When green light shines on a cyan shirt, the color ___________ is seen.

Question 49

The light-sensitive cells in our eyes that allow us to see color are called ___________.

Question 50

When light reflects from mirrors we see a ____________ reflection.

Question 51

When white light shines through a diffraction grating, the blue fringes are __________ the central bright spot than the red fringes.

Question 52

Magenta, yellow, and cyan are the colors used in ____________ color mixing.