PHYS 1160 FINAL EXAM
Question 1
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To study the distribution of interstellar atomic hydrogen (neutral hydrogen) gas in the galaxy
we would use
Select one:
A. an optical telescope and spectrograph to look for emission lines of hydrogen.
B. a radio telescope to look for radiation due to the 21 cm line of hydrogen.
C. an infrared telescope in order to penetrate the dust that obscures much of the Milky
Way.
D. A millimetre wave telescope to look for rotational lines due to hydrogen.
Feedback
B is the correct answer. Neutral atomic hydrogen is detected most easily by its 21cm radio
emission. Rotational lines in the millimetre region are only seen from molecules, and optical
emission lines are only seen where gas is heated by nearby hot stars.
The correct answer is: a radio telescope to look for radiation due to the 21 cm line of
hydrogen.
Question 2
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We believe there is a black hole at the centre of our galaxy because
Select one:
A. the region appears dark in optical images.
B. we detect bursts of gravitational radiation that appear to be due to stars being
swallowed up by the black hole.
C. we have been able to track the orbits of stars near the centre that show they are orbiting
a very massive central object.
D. theoretical models of galaxy formation require the presence of a central black hole for
a galaxy to form.
Feedback
Answer C is the correct answer. We are able to track the orbits of stars around the central
black hole. A black hole could certainly generate gravitational waves as described in answer
B, but this has not been observed, and such events are likely to be rare.
The correct answer is: we have been able to track the orbits of stars near the centre that show
they are orbiting a very massive central object.
Question 3
Correct
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, Galileo used his telescope to discover the following?
[CHECK ALL THAT APPLY]
Select one or more:
A. The four largest satellites of Jupiter
B. The phases of Venus
C. The rings of Saturn
D. The elliptical orbits of the planets
Feedback
Answers A, B are correct. The elliptical orbits of planets were discovered by Kepler, not
Galileo. The rings of Saturn were not recognised by Galileo although he could see that there
was something unusual about its apparent shape.
The correct answer is: The four largest satellites of Jupiter, The phases of Venus
Question 4
Incorrect
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Many large telescopes have been built on the 4200m summit of Mauna Kea in the Hawaiian
Islands because [CHECK ALL THAT APPLY]
Select one or more:
A. The high altitude means the telescopes are closer to the objects being studied and can
thus see more detail.
Question 1
Correct
Mark 5.00 out of 5.00
Flag question
Question text
To study the distribution of interstellar atomic hydrogen (neutral hydrogen) gas in the galaxy
we would use
Select one:
A. an optical telescope and spectrograph to look for emission lines of hydrogen.
B. a radio telescope to look for radiation due to the 21 cm line of hydrogen.
C. an infrared telescope in order to penetrate the dust that obscures much of the Milky
Way.
D. A millimetre wave telescope to look for rotational lines due to hydrogen.
Feedback
B is the correct answer. Neutral atomic hydrogen is detected most easily by its 21cm radio
emission. Rotational lines in the millimetre region are only seen from molecules, and optical
emission lines are only seen where gas is heated by nearby hot stars.
The correct answer is: a radio telescope to look for radiation due to the 21 cm line of
hydrogen.
Question 2
Correct
Mark 5.00 out of 5.00
, Flag question
Question text
We believe there is a black hole at the centre of our galaxy because
Select one:
A. the region appears dark in optical images.
B. we detect bursts of gravitational radiation that appear to be due to stars being
swallowed up by the black hole.
C. we have been able to track the orbits of stars near the centre that show they are orbiting
a very massive central object.
D. theoretical models of galaxy formation require the presence of a central black hole for
a galaxy to form.
Feedback
Answer C is the correct answer. We are able to track the orbits of stars around the central
black hole. A black hole could certainly generate gravitational waves as described in answer
B, but this has not been observed, and such events are likely to be rare.
The correct answer is: we have been able to track the orbits of stars near the centre that show
they are orbiting a very massive central object.
Question 3
Correct
Mark 5.00 out of 5.00
Flag question
Question text
, Galileo used his telescope to discover the following?
[CHECK ALL THAT APPLY]
Select one or more:
A. The four largest satellites of Jupiter
B. The phases of Venus
C. The rings of Saturn
D. The elliptical orbits of the planets
Feedback
Answers A, B are correct. The elliptical orbits of planets were discovered by Kepler, not
Galileo. The rings of Saturn were not recognised by Galileo although he could see that there
was something unusual about its apparent shape.
The correct answer is: The four largest satellites of Jupiter, The phases of Venus
Question 4
Incorrect
Mark 0.00 out of 5.00
Flag question
Question text
Many large telescopes have been built on the 4200m summit of Mauna Kea in the Hawaiian
Islands because [CHECK ALL THAT APPLY]
Select one or more:
A. The high altitude means the telescopes are closer to the objects being studied and can
thus see more detail.
