Question 1

What is the reason for the fact that a reflecting telescope used at prime focus does not suffer from chromatic aberration?

Accepted Answer

A)  The aluminum coating on the mirror absorbs light from all wavelengths except the one of interest to the astronomer, and this light is focused perfectly. 
B)  The light has passed through only one lens. 
C)  All wavelengths of light are reflected by the same amount, regardless of color. 
D)  The lens is so perfectly formed that all colors of light travel through the lens along the same path. 
A)  The aluminum coating on the mirror absorbs light from all wavelengths except the one of interest to the astronomer, and this light is focused perfectly. 
B)  The light has passed through only one lens. 
C)  All wavelengths of light are reflected by the same amount, regardless of color. 
D)  The lens is so perfectly formed that all colors of light travel through the lens along the same path.

Question 2

The first astronomical radio source, identified by Karl Jansky during measurements of sources of radio noise, was

Accepted Answer

A)  the center of our Galaxy. 
B)  the Crab Nebula. 
C)  Jupiter. 
D)  the Orion Nebula. 
A)  the center of our Galaxy. 
B)  the Crab Nebula. 
C)  Jupiter. 
D)  the Orion Nebula.

Question 3

Schmidt-Cassegrain telescopes

Accepted Answer

A)  have parabolic mirrors created by spinning liquid glass. 
B)  give only narrow-angle images. 
C)  are compact. 
D)  allow great magnification. 
A)  have parabolic mirrors created by spinning liquid glass. 
B)  give only narrow-angle images. 
C)  are compact. 
D)  allow great magnification.

Question 4

Suppose Ole Rømer had been able to make accurate speed-of-light measurements from the eclipses of Saturn's satellites as well as Jupiter's. How would these measurements have compared?

Accepted Answer

A)  Calculations from the Saturn data should produce a larger value for the speed of light. 
B)  Calculations from the Saturn data should produce a smaller value for the speed of light. 
C)  The times for the Saturn eclipses should show larger discrepancies from the predicted values, but the calculated speed of light should be the same. 
D)  The times for the Saturn eclipses should show smaller discrepancies from the predicted values, but the calculated speed of light should be the same. 
A)  Calculations from the Saturn data should produce a larger value for the speed of light. 
B)  Calculations from the Saturn data should produce a smaller value for the speed of light. 
C)  The times for the Saturn eclipses should show larger discrepancies from the predicted values, but the calculated speed of light should be the same. 
D)  The times for the Saturn eclipses should show smaller discrepancies from the predicted values, but the calculated speed of light should be the same.

Question 5

The diameter of Earth is about 13,000 km. What distance does light travel in one second, in terms of the diameter of Earth?

Accepted Answer

A)  23 times the diameter 
B)  23,077 times the diameter 
C)  46 times the diameter 
D)  0.043 times the diameter 
A)  23 times the diameter 
B)  23,077 times the diameter 
C)  46 times the diameter 
D)  0.043 times the diameter

Question 6

Gravitational radiation has been found

Accepted Answer

A)  indirectly, by measuring changes in the orbits of neutron stars. 
B)  directly, by using lasers to measure tiny changes in distances on Earth. 
C)  In both A and B. 
D)  by neither A nor B; gravitational radiation is only a theoretical idea. 
A)  indirectly, by measuring changes in the orbits of neutron stars. 
B)  directly, by using lasers to measure tiny changes in distances on Earth. 
C)  In both A and B. 
D)  by neither A nor B; gravitational radiation is only a theoretical idea.

Question 7

A small refracting "spyglass" telescope has an objective lens with a diameter of 2 inches. The world's largest refracting telescope at Yerkes Observatory has an objective lens with a diameter of 40 inches. Assuming that all light striking the objective lenses passes through them, how much larger is the light-gathering power of Yerkes than the spyglass?

Accepted Answer

A)  twice 
B)  40 times 
C)  80 times 
D)  400 times 
A)  twice 
B)  40 times 
C)  80 times 
D)  400 times

Question 8

How does the resolution of a typical radio telescope compare with the resolution of a typical optical telescope?

Accepted Answer

A)  Resolution becomes worse for longer wavelengths, so radio telescopes generally have poorer resolution. 
B)  Resolution becomes better for longer wavelengths, so radio telescopes generally have better resolution. 
C)  Resolution depends on both wavelength and telescope size. Because radio telescopes are so large, the resolution is about the same as for an optical system. 
D)  Resolution depends entirely on the separation of the objects being imaged, so radio and optical telescopes have the same resolution. 
A)  Resolution becomes worse for longer wavelengths, so radio telescopes generally have poorer resolution. 
B)  Resolution becomes better for longer wavelengths, so radio telescopes generally have better resolution. 
C)  Resolution depends on both wavelength and telescope size. Because radio telescopes are so large, the resolution is about the same as for an optical system. 
D)  Resolution depends entirely on the separation of the objects being imaged, so radio and optical telescopes have the same resolution.

Question 9

A spherical mirror suffers from spherical aberration because

Accepted Answer

A)  different colors are focused at different distances from the mirror. 
B)  a mirror of this shape is structurally weak and will sag under its own weight, distorting the image. 
C)  the starlight is distorted by turbulence in Earth's atmosphere. 
D)  different parts of the mirror focus the light at different distances from the mirror. 
A)  different colors are focused at different distances from the mirror. 
B)  a mirror of this shape is structurally weak and will sag under its own weight, distorting the image. 
C)  the starlight is distorted by turbulence in Earth's atmosphere. 
D)  different parts of the mirror focus the light at different distances from the mirror.

Question 10

How much time elapsed from when Ole Rømer discovered that light did not travel at infinite speed to a time when the speed of light was first measured accurately?

Accepted Answer

A)  No time at all-it was Rømer himself who measured this speed accurately! 
B)  28 years 
C)  almost 1000 years 
D)  more than a century but less than two centuries 
A)  No time at all-it was Rømer himself who measured this speed accurately! 
B)  28 years 
C)  almost 1000 years 
D)  more than a century but less than two centuries

Question 11

To what does the term "aberration" in a telescope refer?

Accepted Answer

A)  absorption of light by the glass in the lenses 
B)  magnifying power of the telescope 
C)  fundamental limitation of any telescope to resolve very small details in the image 
D)  defect in design that blurs or distorts the image 
A)  absorption of light by the glass in the lenses 
B)  magnifying power of the telescope 
C)  fundamental limitation of any telescope to resolve very small details in the image 
D)  defect in design that blurs or distorts the image

Question 12

Devices to detect X-rays once they have been focused include all of these EXCEPT

Accepted Answer

A)  CCDs. 
B)  scintillators. 
C)  calorimeters. 
D)  Schmidt corrector plates. 
A)  CCDs. 
B)  scintillators. 
C)  calorimeters. 
D)  Schmidt corrector plates.

Question 13

Increasing the exposure time of an image made through a telescope will

Accepted Answer

A)  brighten the image. 
B)  increase the magnification. 
C)  increase the resolution. 
D)  leave the image unchanged. 
A)  brighten the image. 
B)  increase the magnification. 
C)  increase the resolution. 
D)  leave the image unchanged.

Question 14

A Newtonian telescope uses

Accepted Answer

A)  only one mirror with its front surface shaped into a parabola. 
B)  one curved mirror and one flat mirror at a 45° angle to the first mirror axis. 
C)  two flat mirrors inclined to each other at a right angle. 
D)  two curved mirrors, one convex, the second concave in shape. 
A)  only one mirror with its front surface shaped into a parabola. 
B)  one curved mirror and one flat mirror at a 45° angle to the first mirror axis. 
C)  two flat mirrors inclined to each other at a right angle. 
D)  two curved mirrors, one convex, the second concave in shape.

Question 15

Light enters a plane-parallel block of glass from the vacuum of space and leaves again into space through the opposite side (e.g., in a space-borne instrument). What is the speed of light after it leaves the glass?

Accepted Answer

A)  same speed as it had before it entered the glass 
B)  The exit speed will depend on the thickness of the glass, becoming slower the thicker the glass. 
C)  faster than when it entered because it has passed through the dense glass 
D)  slower because it has passed through the glass and been slowed by it 
A)  same speed as it had before it entered the glass 
B)  The exit speed will depend on the thickness of the glass, becoming slower the thicker the glass. 
C)  faster than when it entered because it has passed through the dense glass 
D)  slower because it has passed through the glass and been slowed by it

Question 16

Which of these types of electromagnetic radiation has the shortest wavelength?

Accepted Answer

A)  visible light 
B)  X-ray 
C)  ultraviolet 
D)  gamma ray 
A)  visible light 
B)  X-ray 
C)  ultraviolet 
D)  gamma ray

Question 17

When a ray of light strikes a smooth mirror surface at an angle to the perpendicular, the ray is reflected

Accepted Answer

A)  on the "other" side of the perpendicular but at the same angle as the incoming ray. 
B)  in reverse along its original (incoming) path. 
C)  at various angles, depending on wavelength. 
D)  so that it travels along the perpendicular to the surface of the mirror. 
A)  on the "other" side of the perpendicular but at the same angle as the incoming ray. 
B)  in reverse along its original (incoming) path. 
C)  at various angles, depending on wavelength. 
D)  so that it travels along the perpendicular to the surface of the mirror.

Question 18

By what factor is the light-gathering power of the 10-m diameter Keck telescope on Mauna Kea in Hawaii greater than an average unaided human eye, with a typical aperture diameter of 5 mm?

Accepted Answer

A)  2.5 × 105 times 
B)  2 × 104 times 
C)  2000 times 
D)  4 × 106 times 
A)  2.5 × 105 times 
B)  2 × 104 times 
C)  2000 times 
D)  4 × 106 times

Question 19

If a person increases the exposure time of an image taken with a certain telescope, one will also increase the

Accepted Answer

A)  brightness. 
B)  magnification. 
C)  resolution. 
D)  sharpness. 
A)  brightness. 
B)  magnification. 
C)  resolution. 
D)  sharpness.

Question 20

Suppose one tries to explain Rømer's measurements in the Ptolemaic model (adding the Galilean moons) with circular orbits and Earth in the center of the system. How could the differences in eclipse times be explained?

Accepted Answer

A)  The later times would still occur when Jupiter is at conjunction and the earlier times when Jupiter is at opposition. 
B)  The later times would occur when Jupiter is moving westward with respect to the stars and the earlier times when Jupiter is moving eastward with respect to the stars. 
C)  The later times would occur when Jupiter is moving eastward with respect to the stars and the earlier times when Jupiter is moving westward with respect to the stars. 
D)  Jupiter in this model is the same distance from Earth at all times so no explanation is possible. 
A)  The later times would still occur when Jupiter is at conjunction and the earlier times when Jupiter is at opposition. 
B)  The later times would occur when Jupiter is moving westward with respect to the stars and the earlier times when Jupiter is moving eastward with respect to the stars. 
C)  The later times would occur when Jupiter is moving eastward with respect to the stars and the earlier times when Jupiter is moving westward with respect to the stars. 
D)  Jupiter in this model is the same distance from Earth at all times so no explanation is possible.

What is the reason for the fact that a reflecting telescope used at prime focus does not suffer from chromatic aberration?

The first astronomical radio source, identified by Karl Jansky during measurements of sources of radio noise, was

Schmidt-Cassegrain telescopes

Suppose Ole Rømer had been able to make accurate speed-of-light measurements from the eclipses of Saturn's satellites as well as Jupiter's. How would these measurements have compared?

The diameter of Earth is about 13,000 km. What distance does light travel in one second, in terms of the diameter of Earth?

Gravitational radiation has been found

How does the resolution of a typical radio telescope compare with the resolution of a typical optical telescope?

A spherical mirror suffers from spherical aberration because

How much time elapsed from when Ole Rømer discovered that light did not travel at infinite speed to a time when the speed of light was first measured accurately?

To what does the term "aberration" in a telescope refer?

Devices to detect X-rays once they have been focused include all of these EXCEPT

Increasing the exposure time of an image made through a telescope will

A Newtonian telescope uses

Light enters a plane-parallel block of glass from the vacuum of space and leaves again into space through the opposite side (e.g., in a space-borne instrument). What is the speed of light after it leaves the glass?

Which of these types of electromagnetic radiation has the shortest wavelength?

When a ray of light strikes a smooth mirror surface at an angle to the perpendicular, the ray is reflected

By what factor is the light-gathering power of the 10-m diameter Keck telescope on Mauna Kea in Hawaii greater than an average unaided human eye, with a typical aperture diameter of 5 mm?

If a person increases the exposure time of an image taken with a certain telescope, one will also increase the

Suppose one tries to explain Rømer's measurements in the Ptolemaic model (adding the Galilean moons) with circular orbits and Earth in the center of the system. How could the differences in eclipse times be explained?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Atomic Physics and Spectra

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

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Exam 3: Light and Telescopes

What is the reason for the fact that a reflecting telescope used at prime focus does not suffer from chromatic aberration?

The first astronomical radio source, identified by Karl Jansky during measurements of sources of radio noise, was

Schmidt-Cassegrain telescopes

Suppose Ole Rømer had been able to make accurate speed-of-light measurements from the eclipses of Saturn's satellites as well as Jupiter's. How would these measurements have compared?

The diameter of Earth is about 13,000 km. What distance does light travel in one second, in terms of the diameter of Earth?

Gravitational radiation has been found

How does the resolution of a typical radio telescope compare with the resolution of a typical optical telescope?

A spherical mirror suffers from spherical aberration because

How much time elapsed from when Ole Rømer discovered that light did not travel at infinite speed to a time when the speed of light was first measured accurately?

To what does the term "aberration" in a telescope refer?

Devices to detect X-rays once they have been focused include all of these EXCEPT

Increasing the exposure time of an image made through a telescope will

A Newtonian telescope uses

Light enters a plane-parallel block of glass from the vacuum of space and leaves again into space through the opposite side (e.g., in a space-borne instrument). What is the speed of light after it leaves the glass?

Which of these types of electromagnetic radiation has the shortest wavelength?

When a ray of light strikes a smooth mirror surface at an angle to the perpendicular, the ray is reflected

By what factor is the light-gathering power of the 10-m diameter Keck telescope on Mauna Kea in Hawaii greater than an average unaided human eye, with a typical aperture diameter of 5 mm?

If a person increases the exposure time of an image taken with a certain telescope, one will also increase the

Suppose one tries to explain Rømer's measurements in the Ptolemaic model (adding the Galilean moons) with circular orbits and Earth in the center of the system. How could the differences in eclipse times be explained?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Atomic Physics and Spectra

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