Question 1

The speed of light was first determined by which scientist?

Accepted Answer

A)  Galileo 
B)  Newton 
C)  Kepler 
D)  Rømer 
E)  Einstein 
A)  Galileo 
B)  Newton 
C)  Kepler 
D)  Rømer 
E)  Einstein

Question 2

If the Sun instantaneously stopped giving off light, what would happen on Earth?

Accepted Answer

A)  It would immediately get dark. 
B)  It would get dark 8 minutes later. 
C)  It would get dark 27 minutes later. 
D)  It would get dark 1 hour later. 
E)  It would get dark 24 hours later. 
A)  It would immediately get dark. 
B)  It would get dark 8 minutes later. 
C)  It would get dark 27 minutes later. 
D)  It would get dark 1 hour later. 
E)  It would get dark 24 hours later.

Question 3

Which of these stars would have the biggest redshift?

Accepted Answer

A)  a star moving slowly toward you 
B)  a star moving fast toward you 
C)  a star moving slowly away from you 
D)  a star moving fast away from you 
E)  a star that is not moving away from you or toward you 
A)  a star moving slowly toward you 
B)  a star moving fast toward you 
C)  a star moving slowly away from you 
D)  a star moving fast away from you 
E)  a star that is not moving away from you or toward you

Question 4

The n = 5 electronic energy level in a hydrogen atom is 1.5 *10 - 19 J higher than the n = 3 level. If an electron moves from the n = 5 level to the n = 3 level, then a photon of wavelength:

Accepted Answer

A)  1.3 nm, which is in the ultraviolet region, is emitted 
B)  1.3 nm, which is in the ultraviolet region, is absorbed 
C)  1,300 nm, which is in the infrared region, is absorbed 
D)  1,300 nm, which is in the infrared region, is emitted 
E)  no light will be absorbed or emitted 
A)  1.3 nm, which is in the ultraviolet region, is emitted 
B)  1.3 nm, which is in the ultraviolet region, is absorbed 
C)  1,300 nm, which is in the infrared region, is absorbed 
D)  1,300 nm, which is in the infrared region, is emitted 
E)  no light will be absorbed or emitted

Question 5

Which of the following photons carry the smallest amount of energy?

Accepted Answer

A)  a blue photon of the visible spectrum, whose wavelength is 450 nm 
B)  an infrared photon, whose wavelength is 10-5 m 
C)  a red photon in the visible spectrum, whose wavelength is 700 nm 
D)  a microwave photon, whose wavelength is 10-2 m 
E)  an ultraviolet photon, whose wavelength is 300 nm 
A)  a blue photon of the visible spectrum, whose wavelength is 450 nm 
B)  an infrared photon, whose wavelength is 10-5 m 
C)  a red photon in the visible spectrum, whose wavelength is 700 nm 
D)  a microwave photon, whose wavelength is 10-2 m 
E)  an ultraviolet photon, whose wavelength is 300 nm

Question 6

The color of visible light is determined by its:

Accepted Answer

A)  speed 
B)  wavelength 
C)  mass 
D)  distance from you 
E)  size 
A)  speed 
B)  wavelength 
C)  mass 
D)  distance from you 
E)  size

Question 7

Figure 1
-If Jupiter has a temperature of 165 K, then at what wavelength does its spectrum peak? Use the electromagnetic spectrum in Figure 1 to answer this question.

Accepted Answer

A)  18 nm-orange visible wavelengths 
B)  1,800 mm-microwave wavelengths 
C)  1,800 nm-infrared wavelengths 
D)  18,000 nm-ultraviolet wavelengths 
E)  18,000 nm-infrared wavelengths 
A)  18 nm-orange visible wavelengths 
B)  1,800 mm-microwave wavelengths 
C)  1,800 nm-infrared wavelengths 
D)  18,000 nm-ultraviolet wavelengths 
E)  18,000 nm-infrared wavelengths

Question 8

Your average body temperature is approximately 310 K, thus most of the light you radiate is at ultraviolet wavelengths.

Accepted Answer

A) True 
 B)False

Question 9

How can the average temperature of the Earth stay approximately constant, even though the Earth is always getting energy from the Sun?

Accepted Answer

The Earth is also giving off energy into

Question 10

A thin cloud of cool gas on top of a hotter blackbody will radiate an emission spectrum.

Accepted Answer

A) True 
 B)False

Question 11

How does the speed of light traveling through a medium (such as air or glass) compare to the speed of light in a vacuum?

Accepted Answer

A)  It is the same as the speed of light in a vacuum. 
B)  It is always less than the speed of light in a vacuum. 
C)  It is always greater than the speed of light in a vacuum. 
D)  Sometimes it is greater than the speed of light in a vacuum, and sometimes it is less, depending on the medium. 
E)  Light can't travel through a medium, it only can go through a vacuum. 
A)  It is the same as the speed of light in a vacuum. 
B)  It is always less than the speed of light in a vacuum. 
C)  It is always greater than the speed of light in a vacuum. 
D)  Sometimes it is greater than the speed of light in a vacuum, and sometimes it is less, depending on the medium. 
E)  Light can't travel through a medium, it only can go through a vacuum.

Question 12

Light with a wavelength of 600 nm has a frequency of:

Accepted Answer

A)  2* 105 Hz 
B)  5 * 107 Hz 
C)  2 * 1010 Hz 
D)  5 * 1012 Hz 
E)  5 * 1014 Hz 
A)  2* 105 Hz 
B)  5 * 107 Hz 
C)  2 * 1010 Hz 
D)  5 * 1012 Hz 
E)  5 * 1014 Hz

Question 13

The period of a wave is inversely proportional to the frequency of that wave.

Accepted Answer

A) True 
 B)False

Question 14

Figure 1
-If the typical temperature of a red giant is 3000 K, at what wavelength is its radiation the brightest? Use the electromagnetic spectrum in Figure 1 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 nm-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 nm-red visible wavelengths

Question 15

The spaceship shown in the figure below is traveling at a speed of 15,000 km/s to the left while it sends out a signal with a wavelength of 4 meters.   If astronomers living on planets A and B measure the radio waves coming from the space ship, what wavelengths will they measure?

Accepted Answer

A)  Planet A measures 6 meters, and planet B measures 2 meters. 
B)  Planet A measures 2 meters, and planet B measures 6 meters. 
C)  Planet A measures 4.2 meters, and planet B measures 3.8 meters. 
D)  Planet A measures 3.8 meters, and Planet B measures 4.2 meters. 
E)  Both Planet A and Planet B measure 4 meters. 
A)  Planet A measures 6 meters, and planet B measures 2 meters. 
B)  Planet A measures 2 meters, and planet B measures 6 meters. 
C)  Planet A measures 4.2 meters, and planet B measures 3.8 meters. 
D)  Planet A measures 3.8 meters, and Planet B measures 4.2 meters. 
E)  Both Planet A and Planet B measure 4 meters.

Question 16

Which of these objects would emit an absorption spectrum?

Accepted Answer

A)  an incandescent light bulb 
B)  a fluorescent light bulb 
C)  an isolated hot gas cloud 
D)  a hot, solid object 
E)  a thin, cool gas cloud that lies in front of a hotter blackbody 
A)  an incandescent light bulb 
B)  a fluorescent light bulb 
C)  an isolated hot gas cloud 
D)  a hot, solid object 
E)  a thin, cool gas cloud that lies in front of a hotter blackbody

Question 17

Imagine you observed three different stars: a red star, a blue star, and a yellow star. You are able to determine that each of these stars has the same radius. Answer each question below and explain how you know.
A: Which star is hottest?
B: Which star is the most luminous?
C: Which star is the brightest?

Accepted Answer

A: The blue one is the hottest because W

Question 18

For a star that lies in the plane of Earth's orbit around the Sun, how does the observed wavelength of the hydrogen absorption line at 656.28 nm in its spectrum change in wavelength (if at all) with the time of year?

Accepted Answer

The wavelength of this absorption line w

Question 19

A light-year is a unit that is used to measure:

Accepted Answer

A)  time 
B)  wavelength 
C)  speed 
D)  energy 
E)  distance 
A)  time 
B)  wavelength 
C)  speed 
D)  energy 
E)  distance

Question 20

Imagine you see a streetlamp that is 100 meters 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 streetlamp?

Accepted Answer

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

Exam 5: Light

The speed of light was first determined by which scientist?

If the Sun instantaneously stopped giving off light, what would happen on Earth?

Which of these stars would have the biggest redshift?

The n = 5 electronic energy level in a hydrogen atom is 1.5 *10 - 19 J higher than the n = 3 level. If an electron moves from the n = 5 level to the n = 3 level, then a photon of wavelength:

Which of the following photons carry the smallest amount of energy?

The color of visible light is determined by its:

Figure 1 -If Jupiter has a temperature of 165 K, then at what wavelength does its spectrum peak? Use the electromagnetic spectrum in Figure 1 to answer this question.

Your average body temperature is approximately 310 K, thus most of the light you radiate is at ultraviolet wavelengths.

How can the average temperature of the Earth stay approximately constant, even though the Earth is always getting energy from the Sun?

A thin cloud of cool gas on top of a hotter blackbody will radiate an emission spectrum.

How does the speed of light traveling through a medium (such as air or glass) compare to the speed of light in a vacuum?

Light with a wavelength of 600 nm has a frequency of:

The period of a wave is inversely proportional to the frequency of that wave.

Figure 1 -If the typical temperature of a red giant is 3000 K, at what wavelength is its radiation the brightest? Use the electromagnetic spectrum in Figure 1 to help you answer this question.

The spaceship shown in the figure below is traveling at a speed of 15,000 km/s to the left while it sends out a signal with a wavelength of 4 meters. If astronomers living on planets A and B measure the radio waves coming from the space ship, what wavelengths will they measure?

Which of these objects would emit an absorption spectrum?

For a star that lies in the plane of Earth's orbit around the Sun, how does the observed wavelength of the hydrogen absorption line at 656.28 nm in its spectrum change in wavelength (if at all) with the time of year?

A light-year is a unit that is used to measure:

Imagine you see a streetlamp that is 100 meters 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 streetlamp?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

The n = 5 electronic energy level in a hydrogen atom is 1.5 *10 ^- ¹⁹ J higher than the n = 3 level. If an electron moves from the n = 5 level to the n = 3 level, then a photon of wavelength: