PHYSICS 1306
EXAM I
Form 1 Dr. Pinsky
Spring 2004
This is a CLOSED BOOK exam. You may use a calculator, however you may not have any
information stored in any user changeable memory prior to the beginning of the
exam for any calculator that you use.
Keep your eyes on your own paper at all times. THERE MAY BE MORE THAN ONE CORRECT ANSWER PER QUESTION, OR
THERE MAY BE NO CORRECT ANSWERS FOR A QUESTION. Mark all correct answers. Grading will be RIGHT MINUS WRONG (answer by answer, not question by question). DO NOT GUESS ! ! !
1. Concerning
stellar motion:
a. radial motion measures
the speed of approach or recession with respect to the observer.
b. It is entirely possible for
two different stars to have the same proper motion.
c. proper
motion refers to the apparent motion of a star in km per second with respect to
the background sky.
d. the antapex is the point in
the sky from which we appear to be coming.
e. a starÕs ŌSpaceĶ motion is
its actual true vector velocity motion with respect to the Sun.
2. Which
of the following indicate the source is receding (NOTE: l is a wavelength, n is a frequency, L means
"laboratory", O means "observed", and c = 3 x 108 m/sec.):
a. lO
= 499 nm and lL = 498 nm
b. nO
= 29.8 MHz and nL = 28.9 MHz
c. lO
= 230 nm and lL = 220 cm
d. nO
= 10 kHz and nL = 400 MHz
e. nO
= 300 kHz and lL = 1 m
3. Which
of the following stars is cooler than a G2 star:
a. O5
b. M9
c. G3
d. G1
e. K1
4. For
star A we have: TA = 6,000K, dist. = 10 pc, dia. = 4 x105 km
For
star B we have: TB = 12,000K, dist. = 1000 pc, dia. = 105 km
a. star A has an apparent
magnitude greater than star B.
b. star A will appear bluer than
star B.
c. star A the same absolute
magnitude as star B.
d. for star A the absolute
magnitude = apparent magnitude.
e. star B has a brighter surface
than star A (per m2).
5. Hipparchus:
a. was the first to prove
that the earth rotated on its axis.
b. is considered to be the
greatest observational astronomer in antiquity.
c. invented the Stellar
Magnitude system we use today.
d. was the first person to
suggest the earth revolved about the sun.
e. was first to suggest the
Milky Way was made of stars.
6. The
Greeks:
a. founded the first
universities.
b. built Stonehenge to observe
the seasons.
c. measured the earth's
diameter.
d. measured the actual distance
to the sun.
e. were the primary source of
planetary position data used by Copernicus.
7. All
Atoms:
a. of normal matter each
have at least one proton in the nucleus.
b. typically absorb light when
electrons fall from one energy level to a vacancy in a lower level.
c. are about the same size
as the wavelength of x-ray electromagnetic radiation.
d. of normal matter if
electrically neutral each have at least one electron in orbit about the nucleus.
e. Were first theorized to exist by Democritus and his
teacher Lucippus.
8. Which
of the following can be determined about a star by examining only the shape of a single spectral line, without knowing which line
it is (i.e., where it belongs in the spectrum):
a. the chemical
composition of the star.
b. whether or not the star has
planets.
c. the star's mass.
d. if the star is rapidly
rotating.
e. if the star has a very high
surface magnetic field.
9. Eclipsing
binaries:
a. only occur near the
full moon.
b. are the only type binaries we
can get mass information from.
c. are always
spectroscopic binaries as well.
d. become completely dark during
an eclipse.
e. Are generally identified by the shape of their
light-curves over time..
10. The
Doppler effect:
a. is sometimes referred
to as the Zeeman Effect.
b. in sound, causes a shift to a
lower pitch for sound emitted by an receding source.
c. was first discovered by
Galileo.
d. is only measurable when the
velocity of the source is >> 1/10 of the speed of light.
e. occurs for all wave phenomena
rather than just visible light.
11. Concerning
Binary Stars:
a. one can always see both
stars in visual binary.
b. are called optical if
both can be seen (in a telescope), and represent true mutually orbiting stars.
c. in the case of both spectrum
and spectroscopic binaries you must be able to resolve both stars
optically from one and other to be able to tell that there are two stars
present.
d. they obey Kepler's Laws.
e. are our only source of stellar mass information.
12. If
a particular star has a surface temperature of 6,000 K and a black body
spectrum that peaks at 500 nm, the spectrum of a:
a. 3,000 K star peaks at
1000 nm.
b. 12,000 K star peaks at 250
nm.
c. 3,000 K star peaks at
250 nm.
d. 12,000 K star peaks at 2000
nm.
e. all stellar spectra peak at
500 nm because of the earth's atmosphere.
13. Which
of the following are variable stars:
a. RR Centauri
b. a Lyrae
c. 26 Lyrae
d. AA Canis Majoris
e. M31
14. Mark
the TRUE statements:
a. All light may appear to move either faster or slower than in a vacuum, depending the relative speeds of the source and observer with respect to each other.
b. Magnetic fields can be felt
only by charges that are moving with respect to the field.
c. Changing electric
fields create magnetic fields.
d. Light is an oscillating and
propagating gravitational wave.
e. Magnetic fields are created
by charges only when they are moving.
15. Issac
Newton:
a. originated the 3 Laws
of Planetary Motion now known as Kepler's Laws.
b. was the primary inspiration
for Galileo.
c. was the first person
who recognized the law of Inertia.
d. invented the reflecting
telescope.
e. included the conservation of
angular momentum directly as one
of his 3 -Laws of Motion.
16. Concerning
stellar magnitudes (Mark the true statements):
a. a star with an apparent magnitude of +5 would appear brighter to the eye than +15 apparent magnitude star.
b. a
difference of 10 in absolute magnitude between two stars means a luminosity
difference of 10,000 times.
c. apparent
magnitude will always be a smaller algebraic number than absolute magnitude.
d. if
one knows both the absolute and apparent magnitude of a star, the starÕs
distance can be calculated.
e. if
two stars have different apparent magnitudes then they must have different absolute magnitudes.
17. A
binary system has equal mass stars each with a mass 4 times that of the
sun and a period of 8 years. If
the separation between them remains constant throughout the entire revolution
then:
a. one cannot calculate
their mutual separation distance given the data at hand.
b. their mutual separation is 10
AU.
c. their mutual separation
is 8 AU.
d. their mutual orbits must be
circles.
e. their mutual separation is
equal to the cube root of 128 AU.
18. Mark
the TRUE statements:
a. If two stars have the same luminosity they will always appear to us to have the same absolute magnitude.
b. The
bluer stars will always seem brighter in the sky than redder stars.
c. Stars
with the same spectral type and luminosity as the sun have absolute magnitudes
of one by definition.
d. Stellar
parallax was first observed by Aristotle.
e. stellar
mass information is only known from measurements of binary systems.
19. If
a hypothetical planet were 2 times the mass and twice the diameter of the
earth.
a. the acceleration of
gravity at its surface would be 2 times that at the earth's surface
b. the acceleration of
gravity at its surface would be one half times that at the earth's
surface
c. the acceleration of
gravity at its surface would be the same that at the earth's surface
d. the density of the
planet would be twice as much as the EarthÕs density
e. the density of the
planet would be one-quarter as much as the EarthÕs density.
20. If
two stars are the at same distance, but one has one ninth of the
diameter and three times the temperature,
this hotter star is:
a. not as luminous
as the cooler star.
b. has the same luminosity
as the cooler star.
c. twice as luminous
as the cooler star.
d. 9 times the luminosity of the
cooler star.
e. more luminous than the cooler
star.
21. Galileo:
a. invented a reflecting telescope where the image is viewed at a right angle with respect to the observing direction.
b. is
considered the father of modern science for his reintroduction of an empirical
philosophy in science.
c. was
the first person to note the precession of the earth's axis of rotation.
d. was
first to report seeing the crescent phases of Venus.
e. discovered
the 1/r2 dependence of the gravitational force.
22. Mark
the TRUE statements:
a. Mass is a vector
quantity.
b. Angular momentum is absolutely
conserved in magnitude but not in direction.
c. Energy is absolutely
conserved.
d. Momentum is absolutely
conserved in both magnitude and direction.
e. Energy is a vector quantity.
23. Concerning
the type of spectra emitted:
a. one would expect a diffuse cloud of gas in space to convert an incident continuous spectrum into an absorption spectrum as light traverses it and emerges from the far side of the cloud.
b. a
black body spectrum is an emission spectrum.
c. most
stars have an absorption spectrum as seen from earth.
d. the
sun's Fraunhofer spectrum is an emission spectrum as seen from earth.
e. all
elements have different absorption spectra.
24. Which
of the following can be resolved in a visible light telescope with an objective
mirror diameter of 1 m? [Hint:
First, calculate the resolution in radians, then convert that to arc secÉ]
(NOTE: For visible light l = 500 nm = 5 x 10-7 m, and
1"arc ~ 5 x 10-6 radians):
a. a car (~ 5 m) where the telescope is in a spy satellite orbiting at an altitude of 500 km directly overhead.
b. the annual parallax of a star
at 1 pc.
c. as a visual binary, two
stars separated by 0.001 arc sec.
d. the proper motion in one year
of a star moving 1.0 arc sec./year.
e. two stars separated by 1 pc
at a distance of 109 pc.
25.
Concerning telescopes:
a. The big advantage the Hubble Space Telescope over those on earth is its weightless environment.
b. All telescopes used for astronomical purposes are used
in the visible wavelengths.
c. Optical telescopes are usually placed on mountaintops
principally to avoid city lights.
d. Newton was one of the first people to figure out how
to make one using a mirror rather than a primary lens.
e. Photographic Film is no longer very widely used for
seeing images on large research telescopes.