ASTRO MIDTERM 2 CH.5

Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength? 1 meter A photon's wavelength cannot be determined from its frequency 300 million meters 1/300,000 meter.

1 meter

An atom which has 4 protons and 6 neutrons will be electrically neutral if it contains ______. 6 electrons 4 electrons at least 1 electron 10 electrons

4 electrons

Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use? 100 joules. 6,000 joules 100 watts 6,000 watts

6,000 joules

Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would occur as you heated the liquid oxygen to high temperature? The liquid oxygen first would solidify. The solid would then vaporize (sublimate) into a gas, which would then become a plasma as the molecules lost their electrons, until finally it consisted of bonded pairs of oxygen nuclei stripped bare of any electrons. It would vaporize (evaporate) into a gas, then the molecules would dissociate into individual oxygen atoms, then the atoms would become increasingly ionized as you continued to raise the temperature. It would vaporize (evaporate) into a gas, then the molecules would lose electrons until no electrons were left, then the molecules would dissociate into individual oxygen nuclei. The liquid molecules would quickly dissociate into a liquid of individual oxygen atoms. These atoms would then vaporize (evaporate) into a gas, and then become ionized to make a plasma.

It would vaporize (evaporate) into a gas, then the molecules would dissociate into individual oxygen atoms, then the atoms would become increasingly ionized as you continued to raise the temperature.

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. The cloud is extremely hot. The cloud is cool and dense, so that you cannot see any objects that lie behind it. The cloud is visible primarily because it reflects light from nearby stars.

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

Which of the following statements about thermal radiation is always true? All the light emitted by hot object has higher energy than the light emitted by a cooler object. A hot object emits more radiation per unit surface area than a cool object. A cold object produces more total infrared and radio emission per unit surface area than a hot object. A hot object produces more total infrared emission than a cooler object.

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

Which of the following transitions within an atom is not possible? An electron begins in the ground state and then gains enough energy to jump to an excited state. An electron begins in an excited state and then gains enough energy to jump to the ground state. An electron begins in the ground state and then gains enough energy to become ionized. An electron begins in an excited state and then gains enough energy to become ionized.

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, whereas an absorption line spectrum consists of dark lines on a rainbow background. The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully. An emission line spectrum consists of a long bright line, whereas an absorption line spectrum consists of a long dark line. The emission line spectrum is produced by electrons jumping up in energy level, whereas the absorption line spectrum is produced by electrons jumping down in energy level.

An emission line spectrum consists of bright lines on a dark background, whereas 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 eight protons and eight neutrons, surrounded by eight electrons; Atom 2: nucleus with eight protons and eight neutrons, surrounded by seven electrons Atom 1: nucleus with four protons and five neutrons, surrounded by four electrons; Atom 2: nucleus with five protons and five neutrons, surrounded by four electrons Atom 1: nucleus with six protons and eight neutrons, surrounded by six electrons; Atom 2: nucleus with seven protons and eight neutrons, surrounded by seven electrons Atom 1: nucleus with seven protons and eight neutrons, surrounded by seven electrons; Atom 2: nucleus with seven protons and seven neutrons, surrounded by seven electrons

Atom 1: nucleus with seven protons and eight neutrons, surrounded by seven electrons; Atom 2: nucleus with seven protons and seven neutrons, surrounded by seven electrons

Consider an atom of carbon in which the nucleus contains six protons and seven neutrons. What is its atomic number and atomic mass number? atomic number = 13; atomic mass number = 6 atomic number = 7; atomic mass number = 13 atomic number = 6; atomic mass number = 13 atomic number = 6; atomic mass number = 7

Atomic number is the number of protons, and atomic mass number is the number of protons plus neutrons.

Consider an atom of oxygen in which the nucleus contains eight protons and eight 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 = 10. Charge = +2; number of remaining electrons = 2. Charge = +2; number of remaining electrons = 6. Charge = +2; number of remaining electrons = 8.

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

Which of the following statements is true of green grass? It absorbs red light and emits green light. It transmits all colors of light except green. It absorbs red light and reflects green light. It means the lawn is healthy.

It absorbs red light and reflects green light

Which of the following statements about electrons is not true? An electron has a negative electrical charge. Within an atom, an electron can have only particular energies. Electrons have little mass compared to protons or neutrons. Electrons can jump between energy levels in an atom only if they receive or give up an amount of energy equal to the difference in energy between the energy levels. Electrons orbit the nucleus rather like planets orbiting the Sun.

Electrons orbit the nucleus rather like planets orbiting the Sun.

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. It is moving away from us. It is much more massive than the Sun. It is much brighter than the Sun.

Its surface is cooler than the surface of the Sun.

What is the difference between energy and power? Power is used to describe energy of light, whereas the term energy has a broader meaning. Power is measured in joules and energy is measured in watts. Power is the rate at which energy is used, so its units are a unit of energy divided by a unit of time. There's no difference; energy and power are different names for the same thing.

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

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 To the Sun A few meters Several centimeters

Several kilometers

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 hotter than Star Y. Star Y is moving away from us faster than Star X. Star X is moving away from us faster than Star Y. Star X is coming toward us faster than Star Y. Star X is moving away from us and Star Y is moving toward us.

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

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 will have an emission line spectrum whereas the slower rotating star will have an absorption line spectrum. The faster rotating star has wider spectral lines than the slower rotating star. There is no way to tell the stars apart spectroscopically because their spectra will be identical. The peak of thermal emission will be at a shorter wavelength for the faster rotating star than for the slower rotating star.

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 has weak gravity. The galaxy is moving away from you. The galaxy is made purely of hydrogen. The galaxy is moving toward you.

The galaxy is moving away from you.

Which of the following best describes why we say that light is an electromagnetic wave? Light is produced only when massive fields of electric and magnetic energy collide with one another. The passage of a light wave can cause electrically charged particles to move up and down. The term electromagnetic wave arose for historical reasons, but we now know that light has nothing to do with either electricity or magnetism. Light can be produced only by electric or magnetic appliances.

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 in the process of formation. The planet is rotating. The planet is in the process of falling apart. We must actually be observing moons orbiting the planet in opposite directions, not the planet itself.

The planet is rotating.

Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true? The radio waves from the radio station have a wavelength of 97 million meters. The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second. The radio station broadcasts its signal with a power of 97 million watts. The "radio waves" received by your radio are not light waves like those we talk about in astronomy, but rather are a special type of sound wave.

The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second.

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 getting colder. The star is moving away from us. The star is moving toward us. The star is getting hotter.

The star is moving toward us.

All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays? The corona lies above the visible surface of the Sun. The corona's structure is largely shaped by magnetic fields. The temperature of the corona's gas is some 1 to 2 million Kelvin. The corona's gas consists mostly of hydrogen and helium.

The temperature of the corona's gas is some 1 to 2 million Kelvin.

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. Shifts in the wavelengths of spectral lines compared to the wavelengths of those same lines measured in a laboratory on Earth can tell us the star's speed toward or away from us. The peak of the star's thermal emission tells us its temperature; hotter stars peak at shorter (bluer) wavelengths. We can identify chemical elements present in the star by recognizing patterns of spectral lines that correspond to particular chemicals.

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

The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun? There is no way to predict the answer to this question because planets and stars are made of such different things. The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the red light that is present in the Sun's spectrum. The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the blue light that is present in the Sun's spectrum. Neptune's spectrum would peak at a much longer wavelength than the Sun's spectrum.

The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the red light that is present in the Sun'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? We can calculate the wavelength of the ripples from their frequency. They have a frequency of 4 hertz. They have a frequency of 2 hertz. They have a wavelength of two cycles per second.

They have a frequency of 2 hertz.

Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)? They have different atomic mass numbers. They have different numbers of electrons. They have different names. They have different numbers of protons in their nucleus.

They have different numbers of protons in their nucleus.

Which of the following statements about X rays and radio waves is not true? X rays and radio waves are both forms of light, or electromagnetic radiation. X rays have shorter wavelengths than radio waves. X rays have higher frequency than radio waves. X rays travel through space faster than radio waves.

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 flat glass mirror a telescope a diffraction grating adaptive optics

a diffraction grating

No object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close approximation to a thermal radiation spectrum? a filament in a standard (incandescent) light bulb a star you a hot, thin (low-density, nearly transparent) gas

a hot, thin (low-density, nearly transparent) gas

According to the laws of thermal radiation, hotter objects emit photons with _________. a shorter average wavelength a higher average speed a lower average energy a lower average frequency

a shorter average wavelength

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

absorbs ultraviolet light

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? gamma rays, X rays, visible light, ultraviolet, infrared, radio gamma rays, X rays, ultraviolet, visible light, infrared, radio radio, infrared, visible light, ultraviolet, X rays, gamma rays infrared, visible light, ultraviolet, X rays, gamma rays, radio

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

The spectra of most galaxies show redshifts. This means that their spectral lines _________. have a higher intensity in the red part of the spectrum have wavelengths that are longer than normal have wavelengths that are shorter than normal always are in the red part of the visible spectrum

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? ultraviolet and X rays visible light infrared and radio infrared and ultraviolet

infrared and radio

An atom that has fewer electrons than protons is called a(n) _________. solid molecule ion plasma

ion

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon? its acceleration the chemical composition of the object that emitted it its wavelength and energy its temperature

its wavelength and energy

Vaporization is the process in which ___________. molecules go from the solid phase to the liquid phase molecules go from the liquid or solid phase to the gas phase electrons are stripped from atoms molecules go from the liquid phase to the solid phase

molecules go from the liquid or solid phase to the gas phase

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

photons

Thermal radiation is defined as _________. radiation with a spectrum whose shape depends only on the temperature of the emitting object radiation that is felt as heat radiation in the form of emission lines from an object radiation produced by an extremely hot object

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

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you? whether the star's spectrum has more emission lines or more absorption lines the peak energy of the star's thermal radiation the wavelengths of spectral lines in the star's spectrum the Doppler shift of the star's spectrum

the wavelengths of spectral lines in the star's spectrum

Gamma rays have a small ______. mass energy frequency wavelength

wavelength