astr ch 5

A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:

redshifted

Suppose you built a scale-model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend?

several kilometers

Notice that the Sun's spectrum appears brightest (or most intense) in the yellow-green region. This fact tells us __________.

the approximate temperature of the Sun's surface

Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?

they have different numbers of protons in their nucleus

Consider an atom of oxygen in which the nucleus contains 8 protons and 8 neutrons. If it is doubly ionized, what is the charge of the oxygen ion and how many electrons remain in the ion?

Charge = +2; number of remaining electrons = 6.

Suppose we want to know what the Sun is made of. What should we do?

Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory.

An atom which has 4 protons and 6 neutrons will be electrically neutral if it contains ______.

4 electrons

Which of the following statements about thermal radiation is always true?

A hot object emits more radiation per unit surface area than a cool object.

Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category. 2) ABSORPTION? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb

ABSORPTION: -visible light does not pass through a black wall -blue light hits a red sweatshirt

Which of the following transitions within an atom is not possible?

An electron begins in an excited state and then gains enough energy to jump to the ground state.

Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?

An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons

Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category. 4) EMISSION? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb

EMISSION: -light comes from your computer screen -light comes from a light bulb

Which of the following statements is true of green grass?

It absorbs red light and reflects green light

Which of the following procedures would allow you to make a spectrum of the Sun similar to the one shown, though with less detail? Pass a narrow beam of sunlight through a prism.

Pass a narrow beam of sunlight through a prism.

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

Its surface is cooler than the surface of the Sun.

What is the difference between energy and power?

Power is the rate at which energy is used, so its units are a unit of energy divided by a unit of time.

Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category. 3) REFLECTION or SCATTERING? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb

REFLECTION or SCATTERING: -red light hits a red sweatshirt -white light hits a white piece of paper

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Star X is moving away from us faster than Star Y.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

The cloud is cool and lies between you and a hot star.

Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category. 1) TRANSMISSION? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb

TRANSMISSION: -visible light meets clear glass -cell phone signals pass through walls

Which of the following best describes why the Sun's spectrum contains black lines over an underlying rainbow?

The Sun's hot interior produces a continuous rainbow of color, but cooler gas at the surface absorbs light at particular wavelengths.

Suppose that two stars are identical in every way - for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth - except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?

The faster rotating star has wider spectral lines than the slower rotating star.

You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum. What can you conclude?

The galaxy is moving away from you

Which of the following best describes why we say that light is an electromagnetic wave?

The passage of a light wave can cause electrically charged particles to move up and down.

If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?

The planet is rotating.

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

The star is moving toward us.

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

The total amount of light in the spectrum tells us the star's radius.

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

The wavelengths of spectral lines in the star's spectrum.

Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?

They have a frequency of 2 hertz - Remember that hertz are units meaning "cycles per second."

If you heat a rock until it glows, its spectrum will be:

a thermal radiation spectrum

Which of the following statements about X rays and radio waves is not true?

X rays travel through space faster than radio waves.

Visible light from a distant star can be spread into a spectrum by using a glass prism or ______.

a diffraction grating

Radio waves are:

a form of light

According to the laws of thermal radiation, hotter objects emit photons with _________.

a shorter average wavelength

Study the graph of the intensity of light versus wavelength for continuous spectra, observing how it changes with the temperature of the light bulb. Recall that one of the laws of thermal radiation states that a higher-temperature object emits photons with higher average energy (Wien's law). This law is illustrated by the fact that for a higher temperature object, the graph peaks at __________.

a shorter wavelength

If we say that a material is opaque to ultraviolet light, we mean that it _________.

absorbs ultraviolet light

What type of visible light spectrum does the Sun produce?

an absorption line spectrum

Consider an atom of carbon in which the nucleus contains 6 protons and 7 neutrons. What is its atomic number and atomic mass number?

atomic number = 6; atomic mass number = 13 Atomic mass number is the number of protons plus neutrons.

Blue light has a higher frequency than red light. Thus, blue light has

higher energy and shorter wavelength than red light

The absorption line spectrum shows what we see when we look at a hot light source (such as a star or light bulb) directly behind a cooler cloud of gas. Suppose instead that we are looking at the gas cloud but the light source is off to the side instead of directly behind it. In that case, the spectrum would __________.

be an emission spectrum

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

gamma rays, X rays, ultraviolet, visible light, infrared, radio

We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light from left to right in order of increasing wavelength. To rank items as equivalent, overlap them. Shortest to Longest wavelength:

gamma rays, x-rays, ultraviolet, visible light, infrared, radio waves

The spectra of most galaxies show redshifts. This means that their spectral lines _________.

have wavelengths that are longer than normal

Which forms of light are lower in energy and frequency than the light that our eyes can see?

infrared and radio

An atom that has fewer electrons than protons is called a/an _________.

ion

Compared to an atom as a whole, an atomic nucleus:

is very tiny but has most of the mass

Some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are:

isotopes of each other

Why is a sunflower yellow?

it reflects yellow light

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?

its wavelength and energy

In the illustration of the solar spectrum, the upper left portion of the spectrum shows the __________ visible light.

lowest frequency

Sublimation is the process in which ___________.

molecules go directly from solid phase to the gas phase

Click "show" for the emission line spectrum, then click "choose gases" and study the emission line spectrum for neon. The neon "OPEN" sign appears reddish-orange because __________.

neon atoms emit many more yellow and red photons than blue and violet photons

When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called _________.

photons

Thermal radiation is defined as _________.

radiation with a spectrum whose shape depends only on the temperature of the emitting object

Gamma rays have a very small ______.

wavelength