Kalfree homework 50

50 midterm questions

Question 1

When Venus is at inferior conjunction, it is   Answer

· 1.

· at its smallest distance from the Earth.

· 2.

· traveling at its greatest speed.

· 3.

· at its greatest angle from the Sun as seen from the Earth.

· 4.

· at its greatest distance from the Earth.

2 points

Question 2

·   In the geocentric model of the solar system, which one of the following phases of Venus should be visible from Earth?   Answer

· 1.

· 2.

· 3.

· 4.

· gibbous phase between third quarter and full

· full

· new

· gibbous phase between first quarter and full

2 points

Question 3

·   When viewed from the Earth, the celestial sphere (the background of stars) moves east to west on a daily basis. This motion is caused by the   Answer

· 1.

· 2.

· 3.

· 4.

· revolution of the Earth around the Sun.

· rotation of the Earth on its axis.

· motion of the stars around the galactic center.

· motion of the Sun through the Galaxy.

·  
2 points

Question 4

·   In the geocentric model for the solar system developed by Ptolemy, to what does the word epicycle refer?   Answer

· 1.

· 2.

· 3.

· 4.

· small circle about which a planet moves while the center of this circle moves

· around the Earth

· large circle (orbit) that carries the planet around the Earth while the planet itself

· is moving in a smaller circle

· complete cycle of planetary motions after which the motions repeat themselves

· (almost) exactly

· length of time from when the planet is farthest from the Earth to the next time it

· is farthest from the Earth

·  
2 points

Question 5

·   Suppose that, at the same time on the same night, we see two supernovas (exploding stars) explode in the night sky. If one is in the Andromeda Galaxy, 2 million light-years away from us, and the other is in the galaxy M82, 6 million light-years away from us, which of the following statements concerning the actual explosion times of these supernovas is correct?   Answer

· 1.

· 2.

· 3.

· 4.

· We cannot tell which star actually exploded first because both stars are so far away.

· The supernova in the Andromeda Galaxy actually occurred before the one in M82.

· The supernova in the Andromeda Galaxy actually occurred after the one in M82.

· We know both stars exploded at the same time because we saw the explosions at

· the same time.

·  
2 points

Question 6

·   A rocket that is accelerated by the force from the ejection of large quantities of hot gases represents an example of which physical law originally stated by Newton?   Answer

· 1.

· 2.

· 3.

· 4.

· Newton’s first law of motion, concerned with state of rest or uniform motion

· Newton’s law of elliptical motion of planets

· Newton’s law of universal gravitation

· Newton’s third law of motion, concerning action and reaction forces

·  
2 points

Question 7

·   In the years after Newton published his laws of motion, it was found that the observed positions of the planet Uranus did not match the predictions of Newton’s theory. The reason for this turned out to be   Answer

· 1.

· 2.

· 3.

· 4.

· the gravitational influence of a previously unknown planet.

· inaccuracies in Newton’s laws (later corrected by general relativity).

· inaccuracies in the observations.

· the perturbing effects of previously unknown satellites (moons) of Uranus.

·  
2 points

Question 8

·   A certain star is found to be 340 ly from the Earth. Expressed in parsecs, the distance is approximately   Answer

· 1.

· 2.

· 3.

· 4.

· 105 pc.

· 0.340 kpc (kiloparsecs).

· 750 pc.

· 1100 pc.

·  
2 points

Question 9

·   From the Earth, we observe occasional retrograde motion in the motion of   Answer

· 1.

· 2.

· 3.

· 4.

· only the inner planets: Mercury and Venus.

· only the outer planets: Mars and beyond.

· all the planets.

· all the planets and the Moon.

·  
2 points

Question 10

·   What is the angle between the line from the Earth to Mercury and the line from Mercury to the Sun when Mercury is at greatest elongation?   Answer

· 1.

· 2.

· 3.

· 4.

· 0°

· 90°

· 180°

· anywhere between 0° and 180°, depending on the particular planetary alignment

·  
2 points

Question 11

·   For many years, the Palomar telescope (5-m diameter) in California was the largest telescope in the world; it has now been surpassed by both Keck telescopes (each of diameter 10 m) in Hawaii. How much greater is the light-gathering power of a Keck telescope than that of the Palomar telescope?   Answer

· 1.

· 2.

· 3.

· 4.

· 4 times greater

· 1.4 times greater

· 8 times greater

· 2 times greater

2 points

Question 12

·   A Cassegrain reflecting telescope is constructed using a   Answer

· 1.

· curved primary mirror followed by a series of both plane and curved mirrors
· that channel the light to a remote location fixed with respect to the Earth.
·

· 2.

· concave primary mirror and a flat, diagonal secondary mirror mounted at a
· 45° angle to the telescope axis.
·

· 3.

· concave primary mirror and concave secondary mirror that reflects light back
· through a hole in the primary mirror.
·

· 4.

· concave primary mirror followed by a smaller convex secondary mirror that
· reflects light back through a hole in the primary mirror.

·  
2 points

Question 13

·   Which of the following techniques is the key factor in a telescope that uses adaptive optics to correct for atmospheric distortion of images, or “seeing”?   Answer

· 1.

· Computer-controlled motors adjust the position and shape of one of the small
· mirrors within the optics many times per second.
·

· 2.

· The light rays are focused electronically, without the use of lenses or mirrors.

· 3.

· Computer-controlled motors rapidly adjust the orientation and position of the
· separate primary mirrors in a multiple-mirror telescope (MMT).
·

· 4.

· A corrector lens compensates for image distortion by electronic control of its shape.

·  
2 points

Question 14

·   How much more efficient in collecting incoming photons is the modern charge-coupled device (CCD) compared to a typical photographic plate?   Answer

· 1.

· more than 100 times

· 2.

· about 35 times

· 3.

· a little better than a factor of 2

· 4.

· about 10 times

·  
2 points

Question 15

·   The first astronomical radio source was detected and identified in the year   Answer

· 1.

· 1897.

· 2.

· 1967.

· 3.

· 1932.

· 4.

· 1945.

·  
2 points

Question 16

·   What fraction of the light falling on a piece of photographic film is typically wasted (does NOT contribute to the formation of the image)?   Answer

· 1.

· 18%

· 2.

· 45%

· 3.

· 2%

· 4.

· 98%

·  
2 points

Question 17

·   Which of the following telescopes consists of a concave, spherical primary mirror and a glass corrector plate to correct for the spherical aberration in the primary?   Answer

· 1.

· Schmidt telescope

· 2.

· Cassegrain telescope

· 3.

· refracting telescope

· 4.

· Newtonian telescope

·  
2 points

Question 18

·   Which of the following sequences of electromagnetic radiation is correct, in order of increasing energy of the photons (or quanta)?   Answer

· 1.

· visible light, UV radiation, X rays, gamma rays

· 2.

· radio waves, microwaves, gamma rays, UV radiation

· 3.

· visible light, microwave, radio waves, infrared rays

· 4.

· gamma rays, radio waves, X rays, infrared rays

·  
2 points

Question 19

·   An electrical spark, such as lightning, generates electromagnetic radiation over a wide range of wavelengths. How much longer will a pulse of radio energy take to travel between two detector stations 100 m apart than will a pulse of ultraviolet radiation from the same spark?   Answer

· 1.

· The time will be identical because both pulses travel at the speed of light.

· 2.

· much shorter because long wavelength radiations travel faster

· 3.

· just a little longer because the high frequency UV radiation travels faster than the
· low frequency radio waves
·

· 4.

· much longer because radio waves have much longer wavelengths and therefore
· travel slower

·  
2 points

Question 20

·   The two ranges of electromagnetic radiation for which the Earth’s atmosphere is reasonably transparent are   Answer

· 1.

· UV and radio waves.

· 2.

· X rays and visible radiation.

· 3.

· visible and far infrared radiation.

· 4.

· visible and radio radiation.

·  
2 points

Question 21

·   Which very significant fact concerning the spectra produced by hot gases, such as elements heated on the solar surface (Fraunhofer, with the solar spectrum) or in a flame (Bunsen and Kirchhoff, with laboratory spectra), was discovered in the 1800s?   Answer

· 1.

· Each chemical element produces its own characteristic pattern of spectral lines that
· remains fixed as the temperature increases.
·

· 2.

· Chemical elements emit spectral lines that move continuously toward the blue end
· of the spectrum as the gas temperature increases.
·

· 3.

· All chemical elements produce the same set of spectral emission or absorption
· lines, but their relative emission intensities differ; hence elements are distinguishable
· from each other by their spectra.
·

· 4.

· The higher the temperature, the greater the redshift of the emitted spectral lines.

·  
2 points

Question 22

·   The hot, dense gas existing on the Sun emits energy   Answer

· 1.

· at all wavelengths, with a peak at one particular wavelength (color).

· 2.

· with the same intensity at all wavelengths. Earth’s atmosphere absorbs radiation at both short and long visible wavelengths to produce the observed spectrum.

· 3.

· only at certain wavelengths and not at other wavelengths.

· 4.

· mostly at the longest and shortest wavelengths, with a minimum in between.

·  
2 points

Question 23

·   The majority of the mass of ordinary matter resides in the   Answer

· 1.

· electron clouds around the nuclei of atoms.

· 2.

· electrons and the nuclei, shared about equally.

· 3.

· electromagnetic energy stored in the atom, from E = mc2.

· 4.

· nuclei of atoms.

·  
2 points

Question 24

·   Ionization of an atom occurs when   Answer

· 1.

· an electron drops from a higher energy level to the ground state.

· 2.

· the nucleus is split, or fission occurs.

· 3.

· an electron is lifted from the ground state to an excited level.

· 4.

· an electron is removed from the atom.

·  
2 points

Question 25

·   The position of an element in the periodic table is directly related to the   Answer

· 1.

· number of electrons in the atomic nucleus and hence to its negative charge.

· 2.

· total number of protons and neutrons in the atomic nucleus.

· 3.

· mass of the nucleus of the atom.

· 4.

· number of protons in the atomic nucleus and hence to its positive charge.

·  
2 points

Question 26

·   If a continuous spectrum of ultraviolet radiation passes through a tube of cool hydrogen gas, what happens to its spectrum?   Answer

· 1.

· All the radiation passes unhindered except the Lyman Lα wavelength, which is
· absorbed by the atoms.
·

· 2.

· All the radiation passes through the tube unhindered because the hydrogen gas
· is cool and cannot absorb energy.
·

· 3.

· Some of the radiation at all wavelengths is absorbed, reducing the intensity at all
· wavelengths uniformly.
·

· 4.

· All the radiation passes through the tube unhindered except at the specific
· wavelengths of the Lyman series, Lα, Lβ, and so on, which are absorbed by the atoms.

·  
2 points

Question 27

·   A violet photon has a wavelength of 400 nm. What is its energy?   Answer

· 1.

· 4.97 × 10–19 joules

· 2.

· 5.21 × 10–19 joules

· 3.

· 3.62 × 10–19 joules

· 4.

· 6.88 × 10–19 joules

·  
2 points

Question 28

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

· 1.

· always appears to be black, whatever its temperature.

· 2.

· always emits the same spectrum of light, whatever its temperature.

· 3.

· absorbs all radiation that falls on it.

· 4.

· reflects all radiation that falls on it, never heating up and always appearing black.

·  
2 points

Question 29

·   The Doppler effect is the   Answer

· 1.

· increase in the observed wavelength of light if the light source is moving toward you.

· 2.

· increase in the observed wavelength of light if the source of light is moving away from you.

· 3.

· change in the wavelength of peak emission of light when the source temperature changes.

· 4.

· splitting of spectral lines into two or more wavelengths because the source of the
· light is in a strong magnetic field.

·  
2 points

Question 30

·   An atom of hydrogen undergoes a collision with another atom in a hot gas in which the energy of collision is about 11 eV. What is the likely outcome of this collision in terms of the atom? (See Figure 4-11, Comins and Kaufmann, Discovering the Universe, 8th ed.)   Answer

· 1.

· The electron in the atom will be excited to the second excited level, n = 3,
· and de-excitation will generate either a Lα UV Lyman photon or an Hα visible
· and a Lα UV photon.
·

· 2.

· The electron in the atom will be excited to the first excited level, and de-excitation
· to the ground state will produce a visible photon of Balmer Hα light.
·

· 3.

· The electron in the atom will be excited to the first excited level, n = 2. Its return
· to the ground state will produce a Lα UV Lyman photon.
·

· 4.

· The electron of the hydrogen atom will be excited beyond the ionization level
· (n = ∞); the atom will be ionized, and the electron will leave the atom completely.

·  
2 points

Question 31

·   What is the cause of an annular eclipse?   Answer

· 1.

· The Moon’s position in its orbit is near apogee, its farthest point from Earth.

· 2.

· The Moon’s position in its orbit is near perigee, its nearest point to Earth.

· 3.

· Earth’s position in its orbit is near aphelion, its farthest point from the Sun.

· 4.

· Earth’s position in its orbit is near perihelion, its nearest point to the Sun.

·  
2 points

Question 32

·   The bright star Procyon is seen to rise on the eastern horizon at 10:00 P.M. on December 1. At approximately what time will this star rise one week later, on December 8?   Answer

· 1.

· 10:28 P.M.

· 2.

· 9:53 P.M.

· 3.

· 10:00 P.M.

· 4.

· 9:32 P.M.

·  
2 points

Question 33

·   The Moon is seen to keep one face toward the Earth at all times. If viewed from a point directly above the plane of the planetary system, how does it have to rotate to maintain this alignment?   Answer

· 1.

· The moon must rotate once per month, or once per orbit around the Earth.

· 2.

· The moon must rotate once per year as the Earth and the Moon orbit the Sun together.

· 3.

· The moon must rotate once per day to maintain its direction toward the Earth.

· 4.

· The moon must not rotate at all because we always see the same face from Earth.

·  
2 points

Question 34

·   The length of time for the Moon to move from new Moon to new Moon is known as one synodic month. Compared to one full orbital period with respect to the star background, or one sidereal month, the synodic month is   Answer

· 1.

· about 2 days shorter.

· 2.

· about twice as long.

· 3.

· about 2 days longer.

· 4.

· exactly the same length.

·  
2 points

Question 35

·   For an observer at a fixed location on the Earth, the angle between the north celestial pole and an observer’s horizon depends on the   Answer

· 1.

· observer’s latitude (north or south of the equator).

· 2.

· time of day.

· 3.

· time of year.

· 4.

· observer’s longitude (east or west of Greenwich).

·  
2 points

Question 36

·   Where would you have to be to see the north celestial pole directly over your head (i.e., in your zenith)?   Answer

· 1.

· at the North Pole of the Earth

· 2.

· on the equator

· 3.

· at a position about 1° away from the Earth’s South Pole, to account for precession

· 4.

· at the South Pole of the Earth

·  
2 points

Question 37

·   If the daytime sky were not so bright, how fast would we see the Sun move across it with respect to the stars as it moves through one full circle in one year?   Answer

· 1.

· about 1° per day

· 2.

· exactly 24° per day or 1° per hour

· 3.

· The Sun would never appear to move with respect to the stars in the sky.

· 4.

· about 15° per hour

·  
2 points

Question 38

·   1 arc minute is equal to   Answer

· 1.

· 1/60°.

· 2.

· 1/3,600°.

· 3.

· 1/60 arc second.

· 4.

· 1/60 of a full circle.

·  
2 points

Question 39

·   The most recent correction to the calendar to keep the yearly date in tune with the seasons (resulting in the present calendar) was instituted by   Answer

· 1.

· Galileo.

· 2.

· Pope Gregory XIII.

· 3.

· Sir Isaac Newton.

· 4.

· Julius Caesar.

·  
2 points

Question 40

·   Which of the following planets will be seen as crescent-shaped from the Earth at certain times in its orbit?   Answer

· 1.

· Mars

· 2.

· Jupiter

· 3.

· Venus

· 4.

· Uranus

·  
2 points

Question 41

·   When Saturn is at its farthest distance from the Earth, it is at   Answer

· 1.

· opposition.

· 2.

· conjunction.

· 3.

· greatest elongation (about 47° from the Sun).

· 4.

· inferior conjunction.

·  
2 points

Question 42

·   What fraction of the light falling on a piece of photographic film is typically wasted (does NOT contribute to the formation of the image)?   Answer

· 1.

· 45%

· 2.

· 98%

· 3.

· 18%

· 4.

· 2%

·  
2 points

Question 43

·   When observing planetary motions from the Earth, the phrase direct motion refers to the   Answer

· 1.

· slow westward motion of the planet from night to night compared to the background stars.

· 2.

· apparent westward motion of the planet (and the Sun, the Moon, and stars) across the
· sky due to the rotation of the Earth.
·

· 3.

· motion of the planet directly toward or away from the Earth in certain parts of the
· planet’s orbit.
·

· 4.

· slow eastward motion of the planet from night to night compared to the background stars.

·  
2 points

Question 44

·   1 arc second is equal to   Answer

· 1.

· 1/3,600°.

· 2.

· 1/360 of a full circle.

· 3.

· 1/60°.

· 4.

· 1/60 of a full circle.

·  
2 points

Question 45

·   The main reason for placing a telescope and scientific equipment into an aircraft to carry out infrared astronomy is to   Answer

· 1.

· avoid the absorption of the IR radiation by water vapor.

· 2.

· avoid stray IR radiation from the warm Earth and its occupants.

· 3.

· obtain photographs of resolution higher than can be obtained on the ground.

· 4.

· obtain longer observing times on specific sources by moving in the direction of
· the Earth’s rotation.

·  
2 points

Question 46

·   From a location in the northern hemisphere, the pole star always appears at an angle above the northern horizon equal to   Answer

· 1.

· 180° plus the longitude of the location.

· 2.

· the latitude of the location.

· 3.

· the longitude of the location.

· 4.

· 90° minus the latitude of the location.

·  
2 points

Question 47

·   The number of degrees in a semicircle is   Answer

· 1.

· 57.3.

· 2.

· 90.

· 3.

· 360.

· 4.

· 180.

·  
2 points

Question 48

·   In single-telescope astronomical systems, either optical or radio, the   Answer

· 1.

· smaller the main mirror or lens or radio dish aperture in general, the sharper the image.

· 2.

· longer the focal length of the primary mirror or lens or radio dish, the sharper the image.

· 3.

· longer the wavelength, the sharper the image.

· 4.

· larger the main mirror or lens or radio dish aperture in general, the sharper the image.

·  
2 points

Question 49

·   Newton stated that if a force were applied to an object in space, the resultant acceleration would depend on the   Answer

· 1.

· initial speed of the object.

· 2.

· initial position of the object.

· 3.

· mass of the object.

· 4.

· size of the object.

·  
2 points

Question 50

·   Which of the following optical elements or combinations make up a Newtonian telescope?   Answer

· 1.

· one concave and one flat mirror

· 2.

· two curved mirrors, one concave, the second convex

· 3.

· one concave focusing mirror

· 4.

· two lenses, to produce an image the correct way around

Turn in your highest-quality paper
Get a qualified writer to help you with

“ Kalfree homework 50 ”

Get high-quality paper

Guarantee! All work is written by expert writers!

Still stressed from student homework?

Get quality assistance from academic writers!

Order now