ASTR 102 Midterm
a typical chemical reaction releases about ______ of energy per atom
1 ev
Universe started expanding ______ years ago
13.7 billion
Once the distance to the Sun is measured, its diameter can be calculated with the...
small angle approximation
compared to an atom as a whole, an atomic nucleus is very _____ but has ______ of the mass
small, most
Graphical representation of Sun's visible light spectrum
smooth part of the curve represents graph of the background rainbow of color; dips in the curve represent the black lines where light is missing from the rainbow
Sublimation is the process by which ______ material enters the ______ phase
solid, gas
Each chemical element produces a unique set of _________
spectral lines
wavelength x frequency = __________
speed of light
Heavier elements subsequently forged in...
stars and supernova
in the bohr model of the atom, light is emitted only when...
an electron makes a transition from one orbit to a lower orbit
Shorter wavelengths mean
higher frequency
Blue light has a higher frequency than red light. Thus blue light has _____ energy and ______ wavelength than red light
higher, shorter
One of the laws of thermal radiation states that a _______ object emits photons with ________ average energy
higher-temperature, higher
The atom in which the electron leaves corresponds with the ________ energy proton, the atom with the shortest arrow indicates the case where the absorbed photon had the ______ energy
highest, lowest
In the beginning, the Universe was composed entirely of ______ and _______
hydrogen and helium
Where should you put a telescope designed for ultraviolet observations?
in Earth orbit
If you wanted a radio telescope to achieve the same angular resolution as a visible-light telescope, it would need to be:
much larger
Visible light spans only a very ________ narrow range of wavelengths.
narrow
A ______ charged zinc plate can be discharged when illuminated with ______ light.
negatively, ultraviolet
Neon appears reddish-orange because
neon atoms emit many more yellow and red photons than blue and violet photons
What powers the sun?
nuclear fusion
the photons of light interact with the electrons in the photoelectric effect...
one at a time
Suppose that two stars are separated in the sky by .01 arc second. If you look at them with a telescope that has an angular resolution of .5 arc second, what will you see?
one point of light that is the blurred image of both stars
How would you make a spectrum of the sun?
pass a narrow beam of sunlight through a prism
Overlaying gas of sun acts like a cloud to...
produce absorption lines
In the Bohr model of the atom, orbits are...
quantized
color light longest wavelength visible light?
red light
A spectral line that appears at a wavelength of 321 nm in the lab appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is
redshifted
A spectral line that appears at a wavelength of 321 nm in the lab appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:
redshifted
Wien's law states that the thermal radiation from a hotter object peaks at a __________ wavelength
shorter
Higher energy means...
shorter wavelength
The fact that the Sun's spectrum appears brightest in the yellow-green region tells us that
the approximate temperature of the Sun's surface
Radar can be used to determine....
the distance to a planet
The farther a photon is from an atom...
the greater the energy
Wien's law states that
the peak wavelength of a spectrum is directly related to an object's temperature
All forms of light move at ________ speed
the same
Emitted photon must have ______ of energy that the electron loses in moving from the _______ to the _______ energy level
the same, higher, lower
If you heat a rock until it glows, its spectrum will be a __________ _______ spectrum
thermal radiation
A spark can be more easily produced in a circuit if it was illuminated with ______ light, but not _____ light
ultraviolet, visible
A diffraction limit is a limit on...
a telescope's angular resolution
If you heat a rock until it glows, its spectrum will be:
a thermal radiation spectrum
How would you find what the Sun is made of?
Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory
Rank by wavelength from shortest to longest
Gamma X Rays Ultraviolet Visible Light Infrared Radio Waves
Emission Line Spectra from top to bottom
Helium Hydrogen Krypton Mercury Neon Water Vapor Xenon
An energy of a photon of light is proportional to its frequency
Planck's constant frequency
Rank by energy from lowest to highest
Radio Waves Infrared Visible Light Ultraviolet X Rays Gamma
Rank by frequency from lowest to highest
Radio Waves Infrared Visible Light Ultraviolet X Rays Gamma
Why does the Sun's spectrum contain black lines over an underlying rainbow?
Sun's hot interior produces a continuous rainbow of color, but cooler gas at surface absorbs light at particular wavelengths
How is an absorption line spectrum produced?
When continuous light from a hot source passes through a cooler cloud of gas
Absorption line spectrum shows what we see when we look at a hot light source directly behind...
a cooler cloud of gas
The twinkling of stars is caused by...
a motion of air in our atmosphere
For a higher temperature object, the graph peaks at ______
a shorter wavelength
The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:
above Earth's atmosphere
The Sun's spectrum is an __________ spectrum
absorption line
What type of visible light spectrum does the Sun produce?
absorption line spectrum
Which technology can allow a single ground-based telescope to achieve images as sharp as those from the Hubble Space Telescope?
adaptive optics
the fraction of incident light that is reflected away rather than absorbed
albedo
Re-emitted light is sent in _______ direction(s)
all
Rutherford's model of the atom: An _______ particle can be scattered through a _______ angle by the compact, ______ charged nucleus
alpha, large, positively
Thomson's model of the atom.. An _____ particle is scattered through only a ______ angle
alpha, small
Interferometry uses two or more telescopes to achieve
an angular resolution equivalent to that of a much larger telescope
Why does conservation of energy demand that it must re-emit light with the same total amount of energy?
because the cloud absorbs light from the hour source
The set of spectral lines that we see in a star's spectrum depend on the star's
chemical composition
The set of spectral lines that we see in a star's spectrum depends on the star's...
chemical composition
Interior of a sun produces a...
continuous spectrum
Compared to the Sun, a star whose spectrum peaks in the infrared is...
cooler
Compared to the Sun, a star whose spectrum peaks in the infrared is:
cooler
Blue light has higher frequency than red light. Thus, blue light has...
higher energy and shorter wavelength than red light
Radar cannot directly be used to...
determine the distance of the Sun
light comes in...
discrete packets of energy
The distance to the Sun can be calculated based on the...
distance to the planet Venus
If we're looking at the gas cloud but the light source is off to the side instead of directly behind it, the spectrum would be an...
emission spectrum
Stephan-Boltzman Law
energy flux
the rate at which energy is emitted from one square meter of the surface of a black body
energy flux
Why is energy order the same as frequency but opposite from wavelength?
energy of a photon of light is proportional to it's frequency
We determine the Sun's overall chemical composition by...
examining all the lines in its spectrum
How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?
four
wavelength times _______ equals the speed of light
frequency
Sun can be pictured as a _______ interior light source surrounded by a thin, cooler layer of ______
gas
earth reaches a "steady state" temperature when...
heat input equals heat output
Compared to an atom as a whole, an atomic nucleus...
is very tiny but has most of the mass
Some nitrogen atoms have 7 neutron and some have 8 neutrons which makes these two forms of nitrogen _______ of each other
isotopes
Some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are:
isotopes of each other
If you see the color red in an X-ray image from the Chandra X-Ray Observatory, it mans:
it depends: the colors are chosen arbitrarily to represent something about the X rays recorded by the telescope
Why is a sunflower yellow?
it reflects yellow light
Extra ______ energy of liberated electrons is proportional to the ______ of the incident light, not the _______.
kinetic, frequency, intensit
radio waves are a form of...
light
Longer wavelengths mean
lower frequency
Upper left portion of the solar spectrum shows the _____ visible light.
lowest frequency
brightness of sun x cross sectional area of earth =
luminosity of Earth
Sun's spectrum appears brightest in the _________ region
yellow-green