Question 1

What overall effect on the visible spectrum of the light from a star results from the light's passage through Earth's atmosphere?

Accepted Answer

A)  The intensity of the long wavelength portion of the spectrum is increased. 
B)  The intensity of the short wavelength portion of the spectrum is reduced. 
C)  The intensity is reduced uniformly across the spectrum. 
D)  The long and short wavelength portions of the spectrum are reduced in intensity, but the middle portion is unaffected. 
A)  The intensity of the long wavelength portion of the spectrum is increased. 
B)  The intensity of the short wavelength portion of the spectrum is reduced. 
C)  The intensity is reduced uniformly across the spectrum. 
D)  The long and short wavelength portions of the spectrum are reduced in intensity, but the middle portion is unaffected.

Question 2

What is the approximate peak wavelength of radiation emitted by (live) human beings, who are (normally) at a temperature of about 310 K?

Accepted Answer

A)  94 $\mu$m 
B)  3.1 $\mu$m 
C)  0.94 $\mu$m 
D)  9.4 $\mu$m 
A)  94 $\mu$m 
B)  3.1 $\mu$m 
C)  0.94 $\mu$m 
D)  9.4 $\mu$m

Question 3

Atoms in a thin, hot gas (such as a neon advertising sign), according to Kirchhoff's laws, emit light at

Accepted Answer

A)  specific wavelengths or colors in a pattern that depends on the element. 
B)  only visible wavelengths. 
C)  all wavelengths, the shape of the continuum spectrum depending on the temperature of the gas. 
D)  only one specific wavelength or color. 
A)  specific wavelengths or colors in a pattern that depends on the element. 
B)  only visible wavelengths. 
C)  all wavelengths, the shape of the continuum spectrum depending on the temperature of the gas. 
D)  only one specific wavelength or color.

Question 4

A typical but very cool star might have a temperature of 3100°C. On the Kelvin scale, this is about

Accepted Answer

A)  3373 K. 
B)  3068 K. 
C)  3100 K. 
D)  2827 K. 
A)  3373 K. 
B)  3068 K. 
C)  3100 K. 
D)  2827 K.

Question 5

The spectrum of the Sun

Accepted Answer

A)  is a continuous spectrum without any absorption lines. 
B)  would show no absorption lines if the spectrum were taken from aboard a spacecraft above Earth's atmosphere. 
C)  contains absorption lines due to Earth's atmosphere as well as the Sun's outer atmosphere. 
D)  contains many bright emission lines as well as absorption lines. 
A)  is a continuous spectrum without any absorption lines. 
B)  would show no absorption lines if the spectrum were taken from aboard a spacecraft above Earth's atmosphere. 
C)  contains absorption lines due to Earth's atmosphere as well as the Sun's outer atmosphere. 
D)  contains many bright emission lines as well as absorption lines.

Question 6

A spectrum produced by heating a gaseous sample of a single element consists of a series of bright lines. If a solid composed of this element is heated, the result will be that

Accepted Answer

A)  the same pattern of bright lines will occur, only brighter. 
B)  the same pattern of bright lines will occur, only dimmer. 
C)  a continuous spectrum will be formed. 
D)  a continuous spectrum will be formed with deep absorption lines at the same places as the bright lines in the spectrum of the gas. 
A)  the same pattern of bright lines will occur, only brighter. 
B)  the same pattern of bright lines will occur, only dimmer. 
C)  a continuous spectrum will be formed. 
D)  a continuous spectrum will be formed with deep absorption lines at the same places as the bright lines in the spectrum of the gas.

Question 7

An atom is now known to consist of a

Accepted Answer

A)  positively charged crystal structure with electrons moving within it. 
B)  small, positively charged black hole with electrons held in orbits around it by intense gravitational forces. 
C)  uniform distribution of positively charged matter with electrons embedded in it. 
D)  small, massive, electrically charged core surrounded by electrons. 
A)  positively charged crystal structure with electrons moving within it. 
B)  small, positively charged black hole with electrons held in orbits around it by intense gravitational forces. 
C)  uniform distribution of positively charged matter with electrons embedded in it. 
D)  small, massive, electrically charged core surrounded by electrons.

Question 8

The gas in the interstellar space between stars is very tenuous (thin) but can be heated to a very high temperature in the vicinity of a hot star. This hot, tenuous gas will emit

Accepted Answer

A)  light at certain wavelengths only (spectral lines), the wavelength of a given spectral line depending on the gas temperature. 
B)  light at certain wavelengths only (spectral lines), the wavelength of the lines being independent of gas temperature. 
C)  light at all wavelengths, the continuous spectrum peaking at a certain wavelength or color depending on temperature. 
D)  no light at any wavelength because hot thin gases do not emit light. 
A)  light at certain wavelengths only (spectral lines), the wavelength of a given spectral line depending on the gas temperature. 
B)  light at certain wavelengths only (spectral lines), the wavelength of the lines being independent of gas temperature. 
C)  light at all wavelengths, the continuous spectrum peaking at a certain wavelength or color depending on temperature. 
D)  no light at any wavelength because hot thin gases do not emit light.

Question 9

The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright emission lines are produced by

Accepted Answer

A)  the low-density atmosphere of the star emitting light in all directions. 
B)  only the part of the low-density atmosphere that is between Earth and the surface of the star. 
C)  all parts of the star, the stellar surface, and the atmosphere, equally. 
D)  the hot, dense, opaque gas at or near the star's surface. 
A)  the low-density atmosphere of the star emitting light in all directions. 
B)  only the part of the low-density atmosphere that is between Earth and the surface of the star. 
C)  all parts of the star, the stellar surface, and the atmosphere, equally. 
D)  the hot, dense, opaque gas at or near the star's surface.

Question 10

The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a neon tube, a fluorescent bulb, or a gas cloud in space) are caused by

Accepted Answer

A)  an electron dropping into the nucleus, producing small nuclear changes. 
B)  electrons jumping to lower energy levels, losing energy as they do so. 
C)  protons jumping from level to level. 
D)  vibrations of the electrons within the atom. 
A)  an electron dropping into the nucleus, producing small nuclear changes. 
B)  electrons jumping to lower energy levels, losing energy as they do so. 
C)  protons jumping from level to level. 
D)  vibrations of the electrons within the atom.

Question 11

The isotope 15N has an atomic number of 7. The nucleus of this isotope contains

Accepted Answer

A)  7 protons and 8 neutrons. 
B)  7 neutrons and 15 protons. 
C)  7 protons and 15 neutrons. 
D)  7 neutrons and 8 protons. 
A)  7 protons and 8 neutrons. 
B)  7 neutrons and 15 protons. 
C)  7 protons and 15 neutrons. 
D)  7 neutrons and 8 protons.

Question 12

The radial velocity of a star or other object is measured by

Accepted Answer

A)  measuring the change in the angular diameter of the object. 
B)  watching the object move compared to the background stars. 
C)  measuring the intensity of the light in different regions of the blackbody curve. 
D)  observing the Doppler shift of spectral lines in the light from the object. 
A)  measuring the change in the angular diameter of the object. 
B)  watching the object move compared to the background stars. 
C)  measuring the intensity of the light in different regions of the blackbody curve. 
D)  observing the Doppler shift of spectral lines in the light from the object.

Question 13

According to Kirchhoff's laws, the continuous spectrum of light from a hot star, after passing through a cool gas cloud,

Accepted Answer

A)  is enhanced at infrared wavelengths by a continuous spectrum emitted by the cool gas. 
B)  contains additional emission lines from energy emitted by the atoms of the cool gas. 
C)  shows absorption features where light has been absorbed by the atoms of the cool gas. 
D)  is unaffected because atoms in the gas cloud are too cool to absorb or emit energy. 
A)  is enhanced at infrared wavelengths by a continuous spectrum emitted by the cool gas. 
B)  contains additional emission lines from energy emitted by the atoms of the cool gas. 
C)  shows absorption features where light has been absorbed by the atoms of the cool gas. 
D)  is unaffected because atoms in the gas cloud are too cool to absorb or emit energy.

Question 14

The star Vega has a higher surface temperature than the Sun. With IR indicating infrared and UV indicating ultraviolet, Vega emits _____ IR and _____ UV flux than the Sun.

Accepted Answer

A)  less; more 
B)  more; more 
C)  more; less 
D)  less; less 
A)  less; more 
B)  more; more 
C)  more; less 
D)  less; less

Question 15

What changes should an observer expect to see in the resulting spectrum of emitted light from a piece of metal when it is heated slowly in an intense flame from 500 K to 1500 K?

Accepted Answer

A)  The intensity of radiation would increase greatly, while the color would change from blue through white to red. 
B)  The intensity of radiation would increase greatly, and the color would change from red through white to blue. 
C)  The intensity of radiation would increase greatly, while the color would remain a dull red. 
D)  The intensity of radiation would increase only slightly, while the color would change from red through white to blue. 
A)  The intensity of radiation would increase greatly, while the color would change from blue through white to red. 
B)  The intensity of radiation would increase greatly, and the color would change from red through white to blue. 
C)  The intensity of radiation would increase greatly, while the color would remain a dull red. 
D)  The intensity of radiation would increase only slightly, while the color would change from red through white to blue.

Question 16

An astronomer, examining two photographs of a small area of sky taken 20 years apart, notices that some of the stars have moved slightly across the sky, relative to most of the other stars in the photographs. This displacement of the stars across the sky is an example of

Accepted Answer

A)  proper motion. 
B)  Doppler shift. 
C)  precession. 
D)  radial velocity. 
A)  proper motion. 
B)  Doppler shift. 
C)  precession. 
D)  radial velocity.

Question 17

To a physicist, a blackbody is defined as an object that

Accepted Answer

A)  always emits the same spectrum of light, whatever its temperature. 
B)  reflects all radiation that falls on it, never heating up and always appearing black. 
C)  always appears to be black, whatever its temperature. 
D)  absorbs all radiation that falls on it. 
A)  always emits the same spectrum of light, whatever its temperature. 
B)  reflects all radiation that falls on it, never heating up and always appearing black. 
C)  always appears to be black, whatever its temperature. 
D)  absorbs all radiation that falls on it.

Question 18

When an object is moving toward an observer, the visible light it emits is Doppler-shifted toward the

Accepted Answer

A)  ultraviolet. 
B)  infrared. 
C)  radio. 
D)  ultrasonic. 
A)  ultraviolet. 
B)  infrared. 
C)  radio. 
D)  ultrasonic.

Question 19

S IV is

Accepted Answer

A)  4-times-ionized sulfur (a sulfur atom that has lost 4 electrons). 
B)  5-times-ionized sulfur (a sulfur atom that has lost 5 electrons). 
C)  a sulfur isotope with 4 neutrons. 
D)  3-times-ionized sulfur (a sulfur atom that has lost 3 electrons). 
A)  4-times-ionized sulfur (a sulfur atom that has lost 4 electrons). 
B)  5-times-ionized sulfur (a sulfur atom that has lost 5 electrons). 
C)  a sulfur isotope with 4 neutrons. 
D)  3-times-ionized sulfur (a sulfur atom that has lost 3 electrons).

Question 20

An astronomer finds a source of light in space that emits light only in specific, narrow emission lines. Kirchhoff's laws lead him to which conclusion?

Accepted Answer

A)  The source cannot consist of gases but must be a solid object. 
B)  The source is made up of a hot, dense gas. 
C)  The source is made up of a hot, low-density gas. 
D)  The source is made up of a hot, dense gas surrounded by a rarefied gas. 
A)  The source cannot consist of gases but must be a solid object. 
B)  The source is made up of a hot, dense gas. 
C)  The source is made up of a hot, low-density gas. 
D)  The source is made up of a hot, dense gas surrounded by a rarefied gas.

What overall effect on the visible spectrum of the light from a star results from the light's passage through Earth's atmosphere?

What is the approximate peak wavelength of radiation emitted by (live) human beings, who are (normally) at a temperature of about 310 K?

Atoms in a thin, hot gas (such as a neon advertising sign), according to Kirchhoff's laws, emit light at

A typical but very cool star might have a temperature of 3100°C. On the Kelvin scale, this is about

The spectrum of the Sun

A spectrum produced by heating a gaseous sample of a single element consists of a series of bright lines. If a solid composed of this element is heated, the result will be that

An atom is now known to consist of a

The gas in the interstellar space between stars is very tenuous (thin) but can be heated to a very high temperature in the vicinity of a hot star. This hot, tenuous gas will emit

The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright emission lines are produced by

The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a neon tube, a fluorescent bulb, or a gas cloud in space) are caused by

The isotope ¹⁵N has an atomic number of 7. The nucleus of this isotope contains

The radial velocity of a star or other object is measured by

According to Kirchhoff's laws, the continuous spectrum of light from a hot star, after passing through a cool gas cloud,

The star Vega has a higher surface temperature than the Sun. With IR indicating infrared and UV indicating ultraviolet, Vega emits _ IR and _ UV flux than the Sun.

What changes should an observer expect to see in the resulting spectrum of emitted light from a piece of metal when it is heated slowly in an intense flame from 500 K to 1500 K?

An astronomer, examining two photographs of a small area of sky taken 20 years apart, notices that some of the stars have moved slightly across the sky, relative to most of the other stars in the photographs. This displacement of the stars across the sky is an example of

To a physicist, a blackbody is defined as an object that

When an object is moving toward an observer, the visible light it emits is Doppler-shifted toward the

S IV is

An astronomer finds a source of light in space that emits light only in specific, narrow emission lines. Kirchhoff's laws lead him to which conclusion?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 4: Atomic Physics and Spectra

What overall effect on the visible spectrum of the light from a star results from the light's passage through Earth's atmosphere?

What is the approximate peak wavelength of radiation emitted by (live) human beings, who are (normally) at a temperature of about 310 K?

Atoms in a thin, hot gas (such as a neon advertising sign), according to Kirchhoff's laws, emit light at

A typical but very cool star might have a temperature of 3100°C. On the Kelvin scale, this is about

The spectrum of the Sun

A spectrum produced by heating a gaseous sample of a single element consists of a series of bright lines. If a solid composed of this element is heated, the result will be that

An atom is now known to consist of a

The gas in the interstellar space between stars is very tenuous (thin) but can be heated to a very high temperature in the vicinity of a hot star. This hot, tenuous gas will emit

The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright emission lines are produced by

The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a neon tube, a fluorescent bulb, or a gas cloud in space) are caused by

The isotope 15N has an atomic number of 7. The nucleus of this isotope contains

The radial velocity of a star or other object is measured by

According to Kirchhoff's laws, the continuous spectrum of light from a hot star, after passing through a cool gas cloud,

The star Vega has a higher surface temperature than the Sun. With IR indicating infrared and UV indicating ultraviolet, Vega emits _____ IR and _____ UV flux than the Sun.

What changes should an observer expect to see in the resulting spectrum of emitted light from a piece of metal when it is heated slowly in an intense flame from 500 K to 1500 K?

An astronomer, examining two photographs of a small area of sky taken 20 years apart, notices that some of the stars have moved slightly across the sky, relative to most of the other stars in the photographs. This displacement of the stars across the sky is an example of

To a physicist, a blackbody is defined as an object that

When an object is moving toward an observer, the visible light it emits is Doppler-shifted toward the

S IV is

An astronomer finds a source of light in space that emits light only in specific, narrow emission lines. Kirchhoff's laws lead him to which conclusion?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

The isotope ¹⁵N has an atomic number of 7. The nucleus of this isotope contains

The star Vega has a higher surface temperature than the Sun. With IR indicating infrared and UV indicating ultraviolet, Vega emits _ IR and _ UV flux than the Sun.