Physics Chapter 11

An object having no real color may be

-gray. -white. -black. -*any of the above

The yellow clothes of a stage performer appear black when illuminated by light that is

-magenta plus cyan. -blue. -*both

If a light signal and a radio signal were emitted simultaneously from the Moon, the first signal to reach Earth would be

-radio -light -*both

Rainbows exist because light is

-refracted. -reflected. -*both

Electromagnetic waves can travel in

-water. -a vacuum. -*both

To see his full height, a boy that is 1 meter tall needs a mirror that is at least

.50 m tall

A diver shines light up to the surface of a smooth pond at a 10° angle to the normal. Some light passes into the air above, and the part that reflects back into the water makes an angle to the normal of

10°.

The person's eye at point P looks into the mirror. Which of the numbered cards can she see reflected in the mirror?

2

A pair of plane mirrors are placed at right angles to each other. A coin placed close to the mirrors has at most

3 images

The amount of light reflected from the front surface of common window glass is about

4%

Ninety percent of light incident on a certain piece of glass passes through it. How much light passes through two pieces of this glass?

81%

Ninety-five percent of light incident on a mirror is reflected. How much light is reflected from three mirrors in succession?

86%

Are the wavelengths of radio and television signals longer or shorter than waves detectable by the human eye?

Both are much longer because their frequencies are much lower than the frequencies of visible light.

The average speed of light slows to 0.80c when it refracts through a particular piece of plastic. What change is there in the light's frequency in the plastic? We see in the following figure that the wavelength of light is shortened when passing through a transparent material. What is the wavelength of the 0.80c light in the piece of plastic in terms of its wavelength in vacuum?

None, refraction does not change the frequency of light. λplastic/λvacuum = 0.80

Which have the longest wavelength: light waves, X-rays, or radio waves?

Radio Waves

Identical rays of light enter three transparent blocks composed of different materials. Light slows down upon entering the blocks. Rank the blocks according to the speed light travels in each, from fastest to slowest.

Red, Blue, Yellow

Do radio waves travel at the speed of sound, at the speed of light, or at some speed in between?

The radio waves travel at the speed of light.

Which will warm up quicker in sunlight?

a piece of colored glass

Light travels faster in

a vacuum

Materials generally become warmer when light is

absorbed by them

The reason that a surface appears darker when wet has to do with

absorption of light re-reflecting inside the wet region

The greenish blue of water is evidence for the

absorption of red light.

Colors seen on TV result from color

addition

A single raindrop illuminated by sunshine disperses

all the colors of the rainbow.

If you wish to send a beam of laser light to a space station that is above the atmosphere near the horizon, aim your laser

along your line of sight

If an electric charge is rapidly shaken up and down,

an electromagnetic wave is produced.

Glass is transparent to light of wave frequencies that

are below its natural frequencies

When visible light is incident upon transparent glass, most atoms in the glass

are forced into vibration.

The direction of vibration for an electron and the plane of polarization of the light it emits

are the same

Distant dark-colored hills appear blue due to the color of the

atmosphere between the observer and the dark hills.

A beam of light emerges from water into air at an angle bent

away from the normal.

ecause of absorption, a Polaroid will actually transmit about 40% of incident nonpolarized light. Two Polaroids with their axes aligned will transmit

between 0% and 40%.

A red crab crawling very deep in the water where sunlight is very dim appears

black

If molecules in the sky scattered red-orange light instead of blue light, sunsets would be

blue

What color light is transmitted by a piece of blue glass?

blue

What single color of light illuminating a ripe banana will make it appear black?

blue

Which has the higher frequency?

blue light.

The solar radiation curve is a graph of

brightness versus frequency.

In 1676, the Danish astronomer Ole Roemer had one of those "Aha!" moments in science. He concluded from accumulated observations of eclipses of Jupiter's moon at different times of the year that light must travel at a finite speed and needed 1300 s to cross the diameter of Earth's orbit around the Sun. Using 300,000,000 km for the diameter of Earth's orbit, calculate the speed of light based on Roemer's 1300-s estimate. How does it differ from a modern value for the speed of light?

c = 2.31×10^5 km/s cR/cm = 0.77

Consider the appearance of an American flag submerged deep in water. The white stars and red stripes appear

cyan and black.

A sheet of red paper will look black when illuminated with

cyan light.

What colors of ink do color ink-jet printers use to produce a full range of colors? Do the colors form by color addition or by color subtraction?

cyan, yellow, magenta, black The colors form by color subtraction

The source of electromagnetic waves is vibrating

electric charges

Object and image for a plane mirror lie

equal distances from the mirror

Different colors of light correspond to different light

frequencies.

An electron vibrating to and fro 1000 times per second generates an electromagnetic wave having a

frequency of 1000 Hz

The inversion of your image in a plane mirror is actually an inversion of

front and back.

A mixture of blue and yellow tiny dots on a printed page appears

green

Light shines on a pane of green glass and a pane of clear glass. The temperature will be higher in the

green glass

The shortest plane mirror in which you can see your entire image is

half your height.

Humans see best in the yellow-green region of the spectrum. So the efficiency of sodium yellow-green lamps that illuminate highways is

higher

The glare seen from water is largely

horizontally polarized.

When a light beam emerges from water into air, the average light speed

increases

Infrared waves are often called heat waves because they

induce resonance in molecules and increase thermal energy in the skin.

The part of the electromagnetic spectrum most absorbed by water is

infrared.

The sky is the deepest blue

just after a rainstorm.

Diffuse reflection occurs when the size of surface irregularities is

large compared to the wavelength of the light used

Compared to the wavelength of incident light, diffuse reflection occurs when the size of surface irregularities is

larger

Relative to its average speed in air, the average speed of a beam of light in glass is

less

The amount of light from an incandescent lamp that is transmitted through an ideal Polaroid filter is half, and through a real Polaroid filter is

less than half.

In the law of reflection, the incident ray, the reflected ray, and the normal between them

lie in the same plane

Atmospheric refraction makes the daylight hours

longer

Relative to ultraviolet waves, the wavelength of infrared waves is

longer

A wave with a long wavelength has a relatively

low frequency

If sunlight were green instead of white, the most comfortable color to wear on a cold day would be

magenta

The inks used in printing the full-color photos in this book are

magenta, cyan, yellow, and black

Glass is opaque to light with wave frequencies that

match its natural frequencies

Refraction causes the bottom of a swimming pool to appear

more shallow

The secondary rainbow is dimmer than the primary rainbow because

of an extra reflection and refraction in the drops.

The whiteness of clouds is evidence in the clouds for a variety of

particle sizes.

Light will not pass through a pair of Polaroids when their axes are

perpendicular.

Complementary colors are two colors that

produce white light when added.

Visible light that shines on a pane of transparent glass

produces a chain of absorptions and re-emissions through the glass

A rough surface for infrared waves may be polished for

radio waves

When a pulse of white light is incident on a piece of glass, the first color to emerge is

red

Magenta light is a mixture of

red and blue light.

The average speed of light is greatest in

red glass

The three colors that comprise the image on a TV screen are

red, blue, and green.

If the atmosphere were about 40 times thicker, at noon the Sun would appear

red-orange.

The color of an opaque object is the same as the light that is

reflected

Distant snow-covered hills appear yellowish due to the color of the

reflected light that survives scattering.

The twinkling of stars is a result of atmospheric

refraction

A mirage is a result of atmospheric

refraction.

When ultraviolet light is incident upon glass, most atoms in the glass

resonate

The sky is blue because air molecules in the sky act as tiny

resonators that scatter blue light.

A wave with a high frequency has a relatively

short wavelength.

Because of refraction, a person standing waist deep in a swimming pool appears to have

shorter legs

Which interacts more with sounds of relatively high frequencies?

small bells

Which interacts more with light of relatively high frequencies?

small particles

Which of the following is fundamentally different from the others?

sound waves

Refraction results from differences in light's

speed

Colors seen on the cover of our physical science book result from color

subtraction

Which becomes warmer in sunlight, sunglasses or clear reading glasses?

sunglasses

Red sunsets are due to light of lower frequencies that

survive being scattered in the air.

Consider a pulse of laser light aimed at the Moon that bounces back to Earth. The distance between Earth and the Moon is 3.84×108m. Find the round-trip time for the light.

t = 2.56 s

It is difficult to see the roadway in front of you when you are driving on a rainy night mainly because

the film of water on the roadway makes the road less diffuse

Rainbows are not usually seen as complete circles because

the ground is usually in the way.

Compared with the speed of light in a vacuum, the speed of light in the empty space between molecules in glass is

the same

Light is incident upon a pane of window glass at a particular angle. The angle of emerging light is

the same

Relative to radio waves, the velocity of visible light waves in a vacuum is

the same

The frequency of an electromagnetic wave and the frequency of the vibrating electrons that produce it are

the same

Different colors of light travel at different speeds in a transparent medium. In a vacuum, different colors of light travel at

the same speed.

Light travels faster in

thin air

The fact that you can get sunburned while submerged in water is evidence that water

transmits ultraviolet light

Polarization is a property of

transverse waves.

When a mirror with a fixed beam on it is rotated through a certain angle, the reflected beam is rotated through an angle

twice as much.

If you walk toward a mirror at a certain speed, the relative speed between you and your image is

twice your speed

Clouds are semi-transparent to

ultraviolet light.

The natural frequency of atoms in glass is in the

ultraviolet region of the spectrum.

The fact that you can get sunburned while in the shade is evidence of

ultraviolet scattering.

Which of these has a higher frequency than visible light?

ultraviolet wave

When you walk toward a mirror you see your image approaching you. If you walk at 2.2 m/s , how fast do you and your image approach each other?

v = 4.4 m/s

The polarization axes of ordinary sunglasses are

vertical

Electromagnetic waves consist of

vibrating electric and magnetic fields

When white light goes from air into water, the color that refracts the most is

violet

Which of the following occupies the smallest percentage of the electromagnetic spectrum?

visible light

Both sound and light can travel in

water

When light is refracted, there is a change in its

wavelength

Which has the shortest wavelength

x-rays

The complementary color of blue is

yellow

A blue object will appear black when illuminated with

yellow light

The color humans are most sensitive to is

yellow-green

The brightest color emitted by the Sun is

yellow-green.