Question 1

Why do some stars in the sky appear blue, whereas other stars appear red?

Accepted Answer

A)  The red stars have higher surface temperatures than the blue stars. 
B)  The blue stars have higher surface temperatures than the red stars. 
C)  The blue stars are closer to us than the red stars. 
D)  The red stars are closer to us than the blue stars. 
E)  The blue stars are moving toward us, while red stars are moving away from us. 
A)  The red stars have higher surface temperatures than the blue stars. 
B)  The blue stars have higher surface temperatures than the red stars. 
C)  The blue stars are closer to us than the red stars. 
D)  The red stars are closer to us than the blue stars. 
E)  The blue stars are moving toward us, while red stars are moving away from us.

Question 2

Radio waves have wavelengths of

Accepted Answer

A)  less than 0.1 nanometer. 
B)  between 0.1 nanometer and 40 nanometers. 
C)  between 40 nanometers and 380 nanometers. 
D)  between 1,000 nanometers and 500 microns. 
E)  more than a few centimeters. 
A)  less than 0.1 nanometer. 
B)  between 0.1 nanometer and 40 nanometers. 
C)  between 40 nanometers and 380 nanometers. 
D)  between 1,000 nanometers and 500 microns. 
E)  more than a few centimeters.

Question 3

What does it mean to say that an object is in thermal equilibrium?

Accepted Answer

A)  It isn't absorbing any energy. 
B)  It isn't radiating any energy. 
C)  It is radiating more energy than it is absorbing. 
D)  It is absorbing more energy than it is radiating. 
E)  It is absorbing the same amount of energy that it is radiating. 
A)  It isn't absorbing any energy. 
B)  It isn't radiating any energy. 
C)  It is radiating more energy than it is absorbing. 
D)  It is absorbing more energy than it is radiating. 
E)  It is absorbing the same amount of energy that it is radiating.

Question 4

Consider an incandescent lightbulb.If you wanted to turn a 10-W lightbulb into a 100-W lightbulb, how would you change the temperature of the filament inside the bulb?

Accepted Answer

A)  Raise its temperature by a factor of 3.2. 
B)  Raise its temperature by a factor of 1.8. 
C)  Raise its temperature by a factor of 10. 
D)  Lower its temperature by a factor of 2.6. 
E)  Lower its temperature by a factor of 5.4. 
A)  Raise its temperature by a factor of 3.2. 
B)  Raise its temperature by a factor of 1.8. 
C)  Raise its temperature by a factor of 10. 
D)  Lower its temperature by a factor of 2.6. 
E)  Lower its temperature by a factor of 5.4.

Question 5

What different processes produce the patterns of light that can be viewed as: continuous spectra; emission spectra; and absorption spectra?

Accepted Answer

Continuous spectra are produced by viewi

Question 6

How do the wavelength and frequency of red light compare to the wavelength and frequency of blue light?

Accepted Answer

A)  Red light has a longer wavelength and higher frequency than blue light. 
B)  Red light has a longer wavelength and lower frequency than blue light. 
C)  Red light has a shorter wavelength and higher frequency than blue light. 
D)  Red light has a shorter wavelength and lower frequency than blue light. 
E)  Red light and blue light will have the same frequencies and wavelengths. 
A)  Red light has a longer wavelength and higher frequency than blue light. 
B)  Red light has a longer wavelength and lower frequency than blue light. 
C)  Red light has a shorter wavelength and higher frequency than blue light. 
D)  Red light has a shorter wavelength and lower frequency than blue light. 
E)  Red light and blue light will have the same frequencies and wavelengths.

Question 7

If the wavelength of a beam of light were to double, how would that affect its frequency?

Accepted Answer

A)  The frequency would be four times higher. 
B)  The frequency would be two times higher. 
C)  The frequency would be two times lower. 
D)  The frequency would be four times lower. 
E)  There is no relationship between wavelength and frequency. 
A)  The frequency would be four times higher. 
B)  The frequency would be two times higher. 
C)  The frequency would be two times lower. 
D)  The frequency would be four times lower. 
E)  There is no relationship between wavelength and frequency.

Question 8

Which two quantities do we need to know in order to use the Stefan-Boltzmann law to determine a blackbody's total luminosity?

Accepted Answer

The Stefan-Boltzmann law relates the flu

Question 9

The average red giant is about 1,000 times more luminous than the average main-sequence star.If both kinds of stars have about the same brightness in our night sky, how much farther away are the red giants compared to the main-sequence stars?

Accepted Answer

A)  32 times farther 
B)  1,000 times farther 
C)  65 times farther 
D)  5.6 times farther 
E)  The red giants and main-sequence stars are approximately the same distance away. 
A)  32 times farther 
B)  1,000 times farther 
C)  65 times farther 
D)  5.6 times farther 
E)  The red giants and main-sequence stars are approximately the same distance away.

Question 10

In the figure below, which blackbody spectrum corresponds to the object with the highest temperature?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 11

The amplitude of a wave is

Accepted Answer

A)  the total distance a wave travels 
B)  a measure of the wave's velocity. 
C)  the number of peaks that pass per second. 
D)  the maximum height of the wave above zero. 
E)  the distance between one peak value and the next peak. 
A)  the total distance a wave travels 
B)  a measure of the wave's velocity. 
C)  the number of peaks that pass per second. 
D)  the maximum height of the wave above zero. 
E)  the distance between one peak value and the next peak.

Question 12

If a lightbulb is moved twice as far away, its luminosity will be

Accepted Answer

A)  doubled. 
B)  quadrupled. 
C)  halved. 
D)  1/4 the original. 
E)  the same. 
A)  doubled. 
B)  quadrupled. 
C)  halved. 
D)  1/4 the original. 
E)  the same.

Question 13

Imagine you see a street lamp that is 100 m away from you and is 10,000 times more luminous than a firefly.How close would you have to be to the firefly to make it look as bright as the street lamp?

Accepted Answer

For objects with equal brightness,L @#LAT-DLM&d<su

Question 14

If the typical temperature of a red giant is 3000 K, at what wavelength is its radiation the brightest? Use the electromagnetic spectrum in the figure below to help you answer this question.

Accepted Answer

A)  1 $\mu$m-infrared wavelengths 
B)  1 $\mu$m-red visible wavelengths 
C)  20$\mu$m-infrared wavelengths 
D)  20 $\mu$m-red visible wavelengths 
E)  700 $\mu$m-red visible wavelengths 
A)  1 $\mu$m-infrared wavelengths 
B)  1 $\mu$m-red visible wavelengths 
C)  20$\mu$m-infrared wavelengths 
D)  20 $\mu$m-red visible wavelengths 
E)  700 $\mu$m-red visible wavelengths

Question 15

If you find that the hydrogen alpha line in a star's spectrum occurs at a wavelength of 656.45 nm, what is the star's approximate radial velocity? Note that the rest wavelength of this line is 656.30 nm.

Accepted Answer

A)  150 km/s away from you 
B)  150 km/s toward you 
C)  350 km/s toward you 
D)  70 km/s away from you 
E)  70 km/s toward you 
A)  150 km/s away from you 
B)  150 km/s toward you 
C)  350 km/s toward you 
D)  70 km/s away from you 
E)  70 km/s toward you

Question 16

How are atoms excited, and why do they become de-excited?

Accepted Answer

An atom becomes excited when an electron

Question 17

Light has aspects of

Accepted Answer

A)  only a wave. 
B)  only a particle. 
C)  both a particle and a wave. 
D)  neither a particle nor a wave. 
E)  none of these are correct. 
A)  only a wave. 
B)  only a particle. 
C)  both a particle and a wave. 
D)  neither a particle nor a wave. 
E)  none of these are correct.

Question 18

The first five energy levels of hydrogen are E1 = 0 eV, E2 = 10.2 eV, E3 =12.1 eV, E4 =12.7 eV, and E5 = 13.1 eV.If the electron is in the n = 4 level, what energies can a single emitted photon have?

Accepted Answer

To emit a photon,the electron needs to d

Question 19

As a blackbody's temperature increases, it also becomes ________ and ________.

Accepted Answer

A)  more luminous; redder 
B)  more luminous; bluer 
C)  less luminous; redder 
D)  less luminous; bluer 
E)  more luminous; stays the same color 
A)  more luminous; redder 
B)  more luminous; bluer 
C)  less luminous; redder 
D)  less luminous; bluer 
E)  more luminous; stays the same color

Question 20

In the energy level diagram shown in the figure below, the electron is excited to the E4 energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest wavelength?

Accepted Answer

A)  E1 
B)  E2 
C)  E3 
D)  E4 
E)  E5 
A)  E1 
B)  E2 
C)  E3 
D)  E4 
E)  E5

Exam 5: Light

Why do some stars in the sky appear blue, whereas other stars appear red?

Radio waves have wavelengths of

What does it mean to say that an object is in thermal equilibrium?

Consider an incandescent lightbulb.If you wanted to turn a 10-W lightbulb into a 100-W lightbulb, how would you change the temperature of the filament inside the bulb?

What different processes produce the patterns of light that can be viewed as: continuous spectra; emission spectra; and absorption spectra?

How do the wavelength and frequency of red light compare to the wavelength and frequency of blue light?

If the wavelength of a beam of light were to double, how would that affect its frequency?

Which two quantities do we need to know in order to use the Stefan-Boltzmann law to determine a blackbody's total luminosity?

The average red giant is about 1,000 times more luminous than the average main-sequence star.If both kinds of stars have about the same brightness in our night sky, how much farther away are the red giants compared to the main-sequence stars?

In the figure below, which blackbody spectrum corresponds to the object with the highest temperature?

The amplitude of a wave is

If a lightbulb is moved twice as far away, its luminosity will be

Imagine you see a street lamp that is 100 m away from you and is 10,000 times more luminous than a firefly.How close would you have to be to the firefly to make it look as bright as the street lamp?

If the typical temperature of a red giant is 3000 K, at what wavelength is its radiation the brightest? Use the electromagnetic spectrum in the figure below to help you answer this question.

If you find that the hydrogen alpha line in a star's spectrum occurs at a wavelength of 656.45 nm, what is the star's approximate radial velocity? Note that the rest wavelength of this line is 656.30 nm.

How are atoms excited, and why do they become de-excited?

Light has aspects of

The first five energy levels of hydrogen are E1 = 0 eV, E2 = 10.2 eV, E3 =12.1 eV, E4 =12.7 eV, and E5 = 13.1 eV.If the electron is in the n = 4 level, what energies can a single emitted photon have?

As a blackbody's temperature increases, it also becomes ________ and ________.

In the energy level diagram shown in the figure below, the electron is excited to the E4 energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest wavelength?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

The first five energy levels of hydrogen are E₁ = 0 eV, E₂ = 10.2 eV, E₃ =12.1 eV, E₄ =12.7 eV, and E₅ = 13.1 eV.If the electron is in the n = 4 level, what energies can a single emitted photon have?

As a blackbody's temperature increases, it also becomes and .

In the energy level diagram shown in the figure below, the electron is excited to the E₄ energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest wavelength?