Astronomy Exam #2

A Sense of Proportion: Arrange the following photons in order of increasing wavelength:

gamma-ray , X-ray , blue , green , yellow , red

Why do astronomers build optical observatories at the tops of mountains? a. To decrease the impact of atmospheric turbulence on seeing. b. To decrease the effect of artificial radio sources on modern sensitive optical detectors. c. To decrease the amount of precipitation. d. To decrease the distance to celestial objects.

A

Why is Kepler's discovery of his first two laws of planetary motion impressive? a. all of these b. The actual orbits of the planets are very nearly circular. c. Nearly all astronomers of his time believed in uniform circular motion. d. The planets' speeds along their orbits do not change much.

A

You have the same mass as a person sitting next to you. Are you gravitationally attracted to them? If so, why don't you instantly zoom over and stick to them? a. I am gravitationally attracted to them. However, since our mass is fairly small, this attraction is insignificant. b. I am gravitationally attracted to them, but we do not instantly zoom over and stick because of air resistance. c. I am not gravitationally attracted to them, because their mass is too small. d. There is no gravitational attraction between us, because only planets cause gravity.

A

A car is on a circular off ramp of an interstate and is traveling at exactly 25 mph around the curve. Does the car have acceleration? a. Yes, because this is an example of inertial uniform motion. b. Yes, because the direction of the car's motion changes. c. No, because the distance between the car and the ramp's center does not change. d. No, because the car's speed does not change.

B

A car is on a circular off ramp of an interstate and is traveling at exactly 25 mph around the curve. Does the car have nonzero velocity? a. Yes, because of the circular form of the ramp. b. Yes, because the car travels. c. No, because the car's speed is constant and this is uniform motion. d. No, because the distance between the car and the ramp's center does not change.

B

Would you be in the dark if your eyes were sensitive only to X-ray wavelengths? a. Yes, you would be in the dark because there is almost no X-ray radiation in the Solar System. b. Yes, you would be in the dark because Earth's atmosphere blocks X-rays and there are almost no X-ray sources on the Earth's surface. c. No, you would not be in the dark because the Sun emits a huge amount of X-ray radiation. d. No, you would not be in the dark because there are many man-made X-ray sources such as household appliances, cars, power lines, mobile phones, and other devices and mechanisms.

B

According to Aristotle, if earth and water were displaced then they would return naturally to their proper place. Today, what do we call this Aristotelean natural motion? a. Inertia. b. Oscillatory motion. c. Motion due to gravity. d. Orbital motion.

C

Does red light have higher or lower energy than blue light? a. Red light has lower energy than blue light because it has higher frequency. b. Red light has higher energy than blue light because it has lower frequency. c. Red light has lower energy than blue light because it has lower frequency. d. Red light has higher energy than blue light because it has higher frequency.

C

An astronaut is in space with a baseball and a bowling ball. The astronaut gives both objects an equal push in the same direction. Does the baseball have the same acceleration as the bowling ball from the push? Why? a. Yes. Since the push is equal, the acceleration is equal too. b. Yes. The balls have the same acceleration, because they are both weightless in space. c. No. The baseball has less acceleration because it has less inertia. d. No. The baseball has greater acceleration than the bowling ball because the bowling ball has the same force acting on a greater mass.

D

Which kind of spectrum is produced by a white household incandescent lightbulb? a. An infrared spectrum. b. An absorption spectrum. c. A blackbody spectrum. d. An emission spectrum.

C

Why can't a spacecraft go "beyond Earth's gravity"? a. The force of gravity is considered to spread with infinite speed, and no object with mass can move with that speed. Therefore, Earth will always pull on a spacecraft. b. The force of gravity is inversely proportional to the product of the mass involved. The masses of both Earth and the spacecraft are finite. Therefore, Earth will always pull on a spacecraft. c. The force of gravity is inversely proportional to the square of distance. This force drops to zero at a distance of infinity. Therefore, Earth will always pull on a spacecraft. d. The force of gravity increases with magnetic fields, and Earth has a significant magnetic field. Therefore, Earth will always pull on a spacecraft.

C

According to Kepler's first law, planets move in elliptical orbits. Why is that considered accelerated motion? a. Kepler's second law shows that a planet's speed changes due to radial acceleration. Planets also change direction as they move. b. Planets are not perfect spheres and their masses are distributed unevenly within them. Kepler's third law shows that orbital periods change. c. Kepler's second law shows that the area of space in the orbits is changing due to tangential acceleration. d. Planets move not only around a sun but have their own rotation. This rotation causes radial acceleration. Kepler's first law shows that the distance between a planet and a sun changes too.

A

Consider the figure below. When an electron in a hydrogen atom moves from the third orbit to the second orbit, the atom emits a Balmer-alpha photon in the red part of the spectrum. In what part of the spectrum would you look to find the photon emitted when an electron in a helium atom makes the same transition? a. Infrared. b. Ultraviolet. c. Visible. d. Microwave.

A

Describe two ways an atom can become excited. a. By absorption of a photon and by collision with other atoms. b. By absorption of a photon and by atom decay. c. By emission of a photon and by atom decay. d. By emission of a photon and by collision with other atoms.

A

Did the magnification, resolving, or light-gathering power change from the left image to the right image in the figure below? How do you know? a. The resolving power increased in the right image because the images of stars are sharper. The magnifying and light-gathering powers did not change. b. The magnifying power increased in the right image because the images of stars are sharper. The resolving and light-gathering powers did not change. c. The magnifying power decreased in the right image because light areas became smaller than in the left image. The resolving and light-gathering powers did not change. d. The light-gathering power decreased in the right image because light areas became smaller than in the left image. The magnifying and resolving powers did not change.

A

How does Kepler's second law of planetary motion overthrow one of the basic beliefs of classical astronomy? a. It states that the planets do not move at a constant speed in their orbits, hence, it contradicts the idea of uniform circular motion. b. Kepler's second law is fully consistent with the basic beliefs of classical astronomy. c. It states that a planet's orbital period depends on its distance from the Sun, hence, it contradicts the perfect heavens principle. d. It states that the planets do not orbit Earth in circular orbits, hence, it contradicts the idea of uniform circular motion.

A

How many protons, neutrons, and electrons are there in a neutral helium atom? a. There are 2 protons, 2 neutrons, and 2 electrons. b. There are 2 protons, no neutrons, and 1 electron. c. There are 2 protons, 2 neutrons, and 4 electrons. d. There are 2 protons, 1 neutron, and 3 electrons.

A

How were Kepler's three laws of planetary motion based on evidence? a. Kepler derived his three laws from years of observations made by Tycho Brahe. b. Kepler stated his three laws based on the Copernican model of the Solar System. c. Kepler derived his three laws from his longtime observations. d. Kepler stated his three laws based on the Alfonsine Tables.

A

Kepler's first two laws of planetary motion can only be applied to which of the following? a. a closed orbit b. any path under the influence of gravity c. all of these d. an orbit around Earth's sun

A

The emission spectra you obtained from a star show a hydrogen spectrum that is shifted toward the blue end of the electromagnetic spectrum compared to the hydrogen spectrum you obtained from the lab. Is the star moving toward Earth, away from Earth, or is there not enough information provided to determine its motion? a. The star is moving towards Earth. b. A hydrogen spectrum can be only redshifted, therefore these emission spectra are incorrect. c. The star is moving away from Earth. d. There is not enough information provided to determine the star's motion.

A

What is the difference between mass and weight? a. Mass is a measure of the amount of matter, and weight is the force on the object due to gravity. b. Weight is a measure of the amount of matter, and mass is the force on the object due to gravity. c. Weight disappears in space but mass does not. d. Mass is the same as weight.

A

What purpose do the colors in a false-color image or map serve? a. To represent different nonoptical aspects of the object, such as variations in intensity of invisible radiation. b. To make the image more beautiful for the human eye. c. To represent the smallest details of the object. d. To explain what nonoptical radiation looks like.

A

Where is the center of mass of the Earth-Moon system? a. Along the line from the center of Earth to the center of the Moon and at a distance of about 4700 km from the center of Earth. b. Along the line from the center of Earth to the center of the Moon and at a distance of about 192,500 km from the center of the Moon. c. Along the line from the center of Earth to the center of the Moon and at a distance of about 12,600 km from the surface of the Moon. d. Along the line from the center of Earth to the center of the Moon and at a distance of about 3900 km above the surface of Earth.

A

Which of the following choices correctly names a molecule and its constituent atoms? a. Water (H20) is a molecule, and it is made up of hydrogen and oxygen atoms. b. Hydrogen (Ne) is a molecule, and it is made up of one neon atom. c. Water (H20) is a molecule, and it is made up of helium and oxygen atoms. d. Oxygen (O2) is a molecule, and it is made up of one oxygen atom.

A

Why did Newton conclude that some force had to pull the Moon toward Earth? a. Newton knew that objects move in a straight line at a constant speed, unless acted upon by an outside force (Newton's first law). However, the Moon followed a curved path around Earth. b. Newton had read the records of ancient astronomers and found out that the Moon had grown since ancient times. There had to be some force pulling the Moon toward Earth. c. Newton noticed an oscillation in the apparent progression of the lunar phases and concluded that there was some force that pulled the Moon toward Earth. d. When an apple hit Newton on the head, he understood that the very same force that had brought the apple crashing towards the ground also pulls the Moon toward Earth.

A

An astronaut is in space with a baseball and a bowling ball. The astronaut pushes both objects in the same direction. If both balls are traveling at the same speed, does the baseball have the same momentum as the bowling ball? a. They both have zero momentum. b. No, the baseball has less momentum than the bowling ball. c. No, the baseball has more momentum than the bowling ball. d. Yes, the baseball has the same momentum as the bowling ball.

B

An electron in a boron atom makes a transition from the fifth excited state to the third excited state. Does the atom become ionized as a result? a. Yes, the atom becomes ionized because due to the electron transition some protons were lost. b. No, the atom does not become ionized because no electrons were lost. Only an electron transition took place. c. Yes, the atom becomes ionized because due to the electron transition some electrons were lost. d. No, the atom does not become ionized because due to the electron transition only neutrons were lost.

B

Describe in detail the motions of the planets according to Ptolemy. a. All the planets orbit around Earth in their own circles with uniform motion. So planets travel at a constant speed. b. All the planets orbit around Earth in their own circles with uniform motion, but have epicycles. Therefore, the planets do not travel at a constant speed. c. All the planets orbit around Earth in their own orbits called deferents. Deferent orbits differ from a circle by the epicycle values, which change slowly over time. d. All the planets orbit around Earth in their own circles called deferents, and these circles intersect the epicycles, which cause slowing and even reversing of the planets' motion.

B

Deuterium has one proton and one neutron in its nucleus surrounded by one electron. Is deuterium an element, an ion, an isotope, and/or a molecule? Why? a. Deuterium is an element next to hydrogen, because it has one proton more than hydrogen. b. Deuterium is an isotope of hydrogen because it has one neutron more than hydrogen. c. Deuterium is an ion of hydrogen because it has more electrons than hydrogen. d. Deuterium is an ion of hydrogen because it has fewer electrons than hydrogen.

B

Does Tycho's model of the Universe explain the phases of Venus that Galileo observed? Why or why not? a. Yes. In Tycho's model, all planets orbit the Sun. The phases of Venus can be explained by its orbiting the Sun. b. Yes. In Tycho's model, all planets except Earth orbit the Sun, and the Sun orbits Earth once each day. Venus shows a full set of phases. c. No. In Tycho's model, Venus moves around an epicycle centered on a line between Earth and the Sun, it would always be seen as a crescent. d. No. In Tycho's model, Venus and the Sun orbit Earth and this cannot explain the phases of Venus.

B

How did the discovery of the Galilean moons disprove Plato's and Aristotle's perfect heavens first principle(s)? a. It showed that Jupiter was not perfect. b. It proved that there could be other centers of motion besides Earth. c. It was not consistent with the perfect heavens principle. d. It proved that Jupiter's moons could go through phases of illumination much like the Moon.

B

How is an isotope different from an ion? a. An ion is an atom that has lost or gained one or more electrons. Isotopes are atoms that have different numbers of protons. b. An ion is an atom that has lost or gained one or more electrons. Isotopes are atoms that have the same number of protons but a different number of neutrons. c. An ion is an atom that has lost or gained one or more protons. Isotopes are atoms that have the same number of protons but a different number of neutrons. d. An ion is an atom that has lost or gained one or more neutrons. Isotopes are atoms that have the same number of neutrons but a different number of electrons.

B

If the celestial sphere were to be considered a hypothesis, would it be correct? a. It could be considered a hypothesis even nowadays because distances to distant stars and their motion do not have any influence on processes on Earth and in the Solar System. b. It could be considered a hypothesis at the time it was proposed. This hypothesis has been shown to be wrong by modern instrumentation. c. It had always been considered just a model to simplify calculation. Even ancient instrumentation is enough to see that stars exist at different distances from Earth. d. It couldn't be considered a hypothesis at the time it was proposed. The perfect celestial sphere did not describe the natural world, but the ideal world undistorted by human senses.

B

In Kepler's third law, what is P for Earth? What is a for Earth? Do these values support or disprove Kepler's third law? a. P=24 hours, a= 1 AU. These values support Kepler's third law. b. P=1 year, a= 1 AU. These values support Kepler's third law. c. P=1 year, a=2 AU. These values disprove Kepler's third law. d. P=365 days, a=1.5x10^8 km. These values disprove Kepler's third law.

B

Since Earth is not the center of the Universe, why doesn't Aristotle's explanation of gravity work? a. If Aristotle's explanation of gravity were true, Earth's shape would be not a sphere, but a cone with an apex directing to the center of the Universe. b. If Aristotle's explanation of gravity were true, then all things would be pulled off Earth and move toward the center of the Universe, which he believed was their proper place. c. If Aristotle's explanation of gravity were true, the precession cycles of Earth's rotation would create significant momentum, and gravitation would double its value. d. If Aristotle's explanation of gravity were true, there would be no gravitation.

B

The nebula shown in the picture below contains mostly hydrogen excited to emit photons. What kind of spectrum would you expect this nebula to produce? a. Superposition of the hydrogen absorption spectrum and the blackbody radiation spectrum. b. Hydrogen emission (bright-line) spectrum. c. Blackbody radiation spectrum. d. Hydrogen absorption spectrum.

B

Why did Plato propose that all heavenly motion was uniform and circular? a. Plato proposed uniform circular motion as the simplest approximation of observed data. b. Plato proposed uniform circular motion because he viewed the world as perfect, and he considered the sphere and uniform circular motion to be perfect. c. Plato chose the spherical form of the Universe arbitrarily. d. Plato knew that Earth is spherical and considered the Universe as layers extending from Earth to the sky.

B

Why do different atoms have different lines in their spectra? a. Different atoms have a different number of electrons. b. The atoms of different elements have a unique set of energy levels for the electrons. c. The atoms of different elements have different masses. d. Different atoms have a different number of neutrons in their nuclei.

B

Why does the amount of blackbody radiation emitted depend on the temperature of the object? a. The higher the temperature of the object, the more atoms are in the excited state and the more energy they absorb in transitions to the ground state. b. The higher the temperature of the object, the more often will the particles collide with each other and radiate more energy in collisions. c. The higher the temperature of the object, the less motion there is among the particles so they radiate less energy. d. The higher the temperature of the object, the more electrons with high energies are emitted.

B

Why must telescopes observing at long infrared (that is, far-infrared) wavelengths be cooled to low temperatures? a. To reduce distortion from uneven expansion and contraction of the mirror and detector parts of the telescope. b. To reduce thermal radiation from the mirror and detector parts of the telescope. c. Because far-infrared light can be gathered only by cold telescopes. d. Because high-energy far-infrared light can overheat the telescope and damage the detectors.

B

Why would you not include sound waves in the electromagnetic spectrum? a. Because they do not have such characteristics as wavelength, frequency, and energy. b. Because they are not electromagnetic waves, i.e., sound waves are not made of varying electric and magnetic fields and they require a medium to propagate. c. Because sound waves are a specific electromagnetic range with frequencies from approximately 20 Hz to 20,000 Hz, which is not usually plotted in the electromagnetic spectrum. d. Because they can travel through empty space.

B

You weigh 100 pounds, your friend weighs 200 pounds, and you are in an arm wrestling contest with each other. Neither person is winning, but each of you is struggling to push the other's forearm over to the tabletop. Which of Newton's laws applies to this scenario and why? a. Newton's first law of motion because we are at rest unless acted on by some force. b. Newton's third law of motion, because the force that I am exerting is equal but opposite in direction to the force that my friend is exerting. c. Newton's second law of motion, because the acceleration depends on the mass of the body and my friend's acceleration is twice as much as mine. d. None of Newton's laws of motion can be applied because we do not move.

B

You weigh 100 pounds, your friend weighs 200 pounds, and you are in an arm wrestling contest with each other. Now in one swift motion you plant your friend's forearm on the table, winning the contest. Which of Newton's laws applies to this motion and why? a. Newton's third law of motion, because our forces occurred in a pair directed in opposite directions. b. Newton's second law of motion applies because the force that I applied to the mass of my friend's arm was sufficient to accelerate it to the table. c. Newton's law of universal gravitation because my friend's forearm was pulled to the table by the gravitational force. d. Newton's first law of motion because my friend stopped exerting the force and his forearm moved uniformly in a straight line.

B

How do Newton's laws of motion and gravity explain the orbital motion of the Moon? a. Deviation of Earth and the Moon from perfect spherical shapes causes tidal forces in addition to gravitational attraction, and according to the third law of motion these forces are mutual. b. Gravitational attraction between the Moon and Earth causes the Moon to rotate around Earth with an increasing speed, as well as to rotate around its own axis with an increasing rate. c. Gravity between Earth and the Moon accelerates the Moon towards Earth enough to pull the Moon from straight-line motion and cause it to follow a curved orbit around Earth. d. Earth's mass curves space-time around Earth and that curvature presses the Moon downwards to its orbit around Earth by gravitational acceleration.

C

How do you know that the planet traveled faster from point A to B rather than from point A' to B' in the figure below? (The planet takes the same amount of time to move from A to B and from A' to B'.) a. The blue sector corresponding to points A and B has a larger area. b. The planet has a higher angular momentum when it moves from A to B. c. It moved farther along its orbit from A to B in the same amount of time. d. Speeds of the planet cannot be determined based on the given information.

C

How does Kepler's first law of planetary motion overthrow one of the basic beliefs of classical astronomy? a. Kepler's first law is fully consistent with the basic beliefs of classical astronomy. b. It states that the planets do not move at a constant speed in their orbits, hence, it contradicts the idea of uniform circular motion. c. It states that the planets do not orbit Earth and also do not follow circular orbits; hence, it contradicts the idea of uniform circular motion. d. It states that a planet's orbital period depends on its distance from the Sun, hence, it contradicts the perfect heaven principle.

C

How many accelerators does a car have? What are they? a. The car does not have any accelerators. b. Two: the gas pedal and the brake pedal. c. At least three: the gas pedal, the brake pedal, and the steering wheel. d. One: the gas pedal.

C

If the frequency of an electromagnetic wave increases, does the number of waves passing by you increase, decrease, or stay the same? a. The number of waves passing by stays the same because the speed of light stays the same. b. The number of waves passing by decreases because the speed of light decreases. c. The number of waves passing by increases because the speed of light stays the same. d. The number of waves passing by increases because the speed of light increases.

C

What is the biggest advantage of a reflecting telescope? a. all of these b. The focal length is longer. c. The light never passes through glass before the eyepiece. d. The eyepiece is smaller.

C

What kind of spectrum does a neon sign produce? a. A continuous spectrum. b. An absorption spectrum. c. An emission spectrum. d. A blackbody spectrum.

C

If you drop a feather and a steel hammer at the same moment, they should hit the ground at the same instant. Why doesn't this work on Earth, and why does it work on the Moon? a. The magnetic field of Earth affects the steel hammer and increases its acceleration. Because of that, the hammer falls faster than the feather. The Moon doesn't have a magnetic field. b. The feather has an airfoil creating lift in Earth's atmosphere, which slows the feather's fall. Because of that the hammer falls faster. A bird's feather doesn't create lift in the Moon's atmosphere. c. Air resistance slows the feather on Earth but doesn't affect the hammer very much. Thus, they land at a different time. On the Moon, there is no air (and no air resistance). d. Air resistance slows the feather on Earth and the magnetic field accelerates the hammer on Earth. Because of that, they land at different times. The Moon doesn't have an atmosphere or a magnetic field.

C

In a telescope, which of the following is the optical element with the shortest focal length? a. the secondary lens or mirror b. the primary lens or mirror c. the eyepiece d. the focus

C

The star images in this photo are tiny disks, but the diameters of these disks are not related to the diameter of the stars. Explain why the telescope can't resolve the diameter of the stars. What causes the apparent diameters of the stars? a. The angular sizes of the stars in the photo are greater than the resolving power. The size of the star's image is related to its distance from Earth. b. The angular sizes of the stars in the photo are greater than the resolving power. The size of the star's image is related to its brightness. c. The angular sizes of the stars in the photo are smaller than the resolving power. The size of the star's image is related to its brightness. d. The angular sizes of the stars in the photo are smaller than the resolving power. The size of the star's image is related to its distance from Earth.

C

What colors are the 589.0 nm and 589.6 nm sodium lines in the Sun's absorption spectrum shown in the figure below? Where do those sodium lines originate? a. Blue. These are lines produced by sodium in the Sun's photosphere where the continuous background spectrum is produced. b. Blue. These are lines produced by sodium in the upper Earth atmosphere, which is much cooler than the Sun. c. Yellow. These are lines produced by sodium in the Sun's atmosphere, between the observer and the Sun's photosphere where the continuous background spectrum is produced. d. Yellow. These are lines produced by sodium in the upper Earth atmosphere, which is much cooler than the Sun.

C

Why do nocturnal animals usually have large pupils in their eyes? How is that related to the way astronomical telescopes work? a. Large pupils of nocturnal animals are the result of biological evolution that is not related to the designing of telescopes. b. Large pupils of nocturnal animals have higher magnifying power. Likewise, telescopes with large primaries can detect faraway stars with small angular diameters. c. Large pupils of nocturnal animals allow more light to be gathered. Likewise, telescopes with large primaries gather more light and are able to study fainter objects. d. Large pupils of nocturnal animals have higher resolving power and effectively eliminate diffraction fringes. Likewise, telescopes with large primaries can distinguish faraway stars that are close to each other.

C

You are driving your car. If you make a right turn at a constant speed, is that an acceleration? a. No, because the speed of the car did not change. b. Yes, because the road reacts to the car's movement due to Newton's third law. c. Yes, because the velocity of the car changed. d. No, because the weight of the car did not change.

C

Compared to infrared radiation, does ultraviolet radiation have longer or shorter wavelengths? Does ultraviolet radiation have higher or lower energy per photon? a. Ultraviolet radiation has longer wavelengths and lower energy than infrared radiation. b. Ultraviolet radiation has longer wavelengths and higher energy than infrared radiation. c. Ultraviolet radiation has shorter wavelengths and lower energy than infrared radiation. d. Ultraviolet radiation has shorter wavelengths and higher energy than infrared radiation.

D

How many atmospheric windows are shown in the figure below, and which bands of the electromagnetic spectrum are they in? a. There are three windows located in the ultraviolet, visible, and radio wave bands of the electromagnetic spectrum. b. There is one window located in the visible band of the electromagnetic spectrum. c. There is one window located in the microwave band of the electromagnetic spectrum. d. There are two windows located in the visible and radio wave bands of the electromagnetic spectrum.

D

How were Galileo's observations of the moons of Jupiter evidence against the Ptolemaic model? a. These observations were not consistent with the idea of epicycles in the Ptolemaic system. b. It was shown that some planets were not perfect. c. It proved that Jupiter's moons could go through phases of illumination much like the Moon. d. Moons circling Jupiter did not fit the implicit Aristotelian belief that all motion is centered on Earth.

D

If the frequency of an electromagnetic wave increases, does the energy of the photon increase, decrease, or stay the same? a. The energy of the photon stays the same, because its speed is constant. b. The energy of the photon decreases. c. The energy of the photon stays the same because its wavelength decreases. d. The energy of the photon increases.

D

On what did Plato base his knowledge? On what do modern astronomers base their knowledge? a. On Greek myths and public opinion of his time. Modern astronomers base their knowledge on data. b. On a belief that the heavens were only made up of the most perfect geometric form. Modern astronomers base their knowledge on theories. c. On a hypothesis of his predecessor philosophers, such as Thales and Philolaus. Modern astronomers base their knowledge on theories. d. On a belief that the heavens were only made up of the most perfect geometric form. Modern astronomers base their knowledge on data.

D

The infrared radiation coming out of your ear can tell a doctor your temperature. How does that work? a. The medical device measures the energy radiated from the ear and then calculates temperature according to the Stefan-Boltzmann law. b. The medical device measures the wavelength of the radiation from the ear and then calculates temperature according to the Stefan-Boltzmann law. c. The medical device measures the energy radiated from the ear and then calculates temperature according to Wien's law. d. The medical device measures the wavelength of the radiation from the ear and then calculates temperature according to Wien's law.

D

This X-ray image shows the remains of an exploded star. Explain why images recorded by telescopes in space are often displayed in "false" color rather than in the "colors" (that is, wavelengths) received by the telescope. What color would we see this image in if the image were not falsely colored? a. False color images are used to compensate for chromatic aberrations. If the image were not falsely colored, we would see it in true colors. b. False color images are used to compensate for chromatic aberrations. If the image were not falsely colored, we would probably see nothing. c. False color images are often used to represent different levels of intensity of visible light. If the image were not falsely colored, we would see it in true colors. d. False color images are often used to represent different levels of intensity of light with nonvisible wavelengths. If the image were not falsely colored, we would probably see nothing.

D

When does the planet move at its fastest speed? a. When it is farthest from the sun. b. When it is at an equal distance from the two foci. c. When it is sweeping out the minimum amount of area. d. When it is closest to the sun.

D

Which of the following is the first thing light hits when it enters a telescope? a. the secondary lens or mirror b. the focus c. the eyepiece d. the primary lens or mirror

D

Why might you say that an atom is mostly composed of empty space? a. An atom is almost empty because the size of the nucleus is large as compared to the orbit. b. Only atoms with few orbital electrons are composed of empty space; heavier atoms are not so empty. c. The space between the nucleus and the electrons' orbit is constantly increasing and it is almost empty. d. The volume between the nucleus and the electron orbit takes up almost all the space in an atom and hence, it is empty.

D