Astronomy Test 2 (Ch. 5)
Terms in this set (64)
Which of the six numbered features represents emission lines?
1 - above ultraviolet
Which of the six numbered features represents absorption lines?
5 - above infared
Which portion(s) of the spectrum represent(s) reflected sunlight?
2, 3, & 4
What does the wavelength of the peak labeled 6 tell us about Mars?
its surface temperature
What feature(s) of this spectrum indicate(s) that Mars appears red in color?
the fact that the intensity of region 4 is higher than that of region 2
1. The number of protons in an atom is called the atom's __________.
2. Each chemical element has a unique_______.
3. The sum of the number of protons and neutrons in an atom is called the atomic mass number.
4. An atom with more electrons than protons has a __________.
5. Most hydrogen atoms have only a single proton in their nucleus, so a hydrogen atom that also has one neutron is an ______ of hydrogen.
1. Atomic Number
2. Atomic Number
3. Atomic Mass Number
4. Negative Electric Charge
What is the correct composition of a neutral atom of helium-4?
2 protons, 2 electrons, 2 neutrons
Which of the following type of spectrum would you expect if you view star light that has passed through a cool cloud of interstellar gas on its way to Earth?
an absorption line spectrum
Suppose a source at rest emits a spectrum that looks like the following:
Which of the following indicates the source moving away from you the fastest?
Answer is a picture
lines should be furthest away from the picture given
Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?
the wavelengths of spectral lines in the star's spectrum
Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?
An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
Compared to red light, blue light has higher frequency and
higher energy and shorter wavelength.
Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?
They have a frequency of 2 hertz. (hertz = cycles per second)
Which forms of light are lower in energy and frequency than the light that our eyes can see?
Infrared and radio
If we say that a material is opaque to ultraviolet light, we mean that it _________.
absorbs ultraviolet light
A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:
Which of the following are forms of light (electromagnetic radiation)?
Red light has a _____ wavelength and a _____ frequency than does blue light.
X ray photons have a _____ wavelength, _____ frequency, and _____ energy than do ultraviolet photons.
shorter, higher, higher
If you have a telescope that is observing light with wavelengths of a few meters, you are observing __________.
Suppose that you had "X-ray vision" that allowed you to see X rays. What would you notice when you looked at a friend standing near you that you could not notice with your visible light vision alone?
The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:
Above Earth's atmosphere
A star whose spectrum peaks in the infrared is:
cooler than our sun
Which of the following forms of light can be observed with telescopes at sea level?
If our eyes were sensitive only to X rays, the world would appear __________.
dark because X-ray light does not reach Earth's surface
If you had only one telescope and wanted to take both visible-light and ultraviolet pictures of stars, where should you locate your telescope?
The James Webb Space Telescope is designed primarily to observe __________.
Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category.
Visible light meets clear glass.Cell phone signals pass through walls.
Visible light does not pass through a black wall. Blue light hits a red sweatshirt.
Reflection or scattering:
Red light hits a red sweatshirt. White light hits a white piece of paper.
Light comes from a light bulb. Light comes from your computer screen.
Listed following are distinguishing characteristics and examples of reflecting and refracting telescopes. Match these to the appropriate category.
Most commonly used by professional astronomers today. The Hubble Space Telescope. world's largest telescope.
The world's largest is 1-meter in diameter. Galileo's telescopes. very large telescopes become "top-heavy", incoming light passes through glass.
The stars in our sky twinkle in brightness and color because of _________.
turbulence in Earth's atmosphere
Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?
They have different numbers of protons in their nucleus.
Radio waves are:
A form of light
The _______ of the Hubble Space Telescope is better for shorter (bluer) wavelengths of light than for longer (redder) wavelengths of light.
The large research observatories on Mauna Kea use giant ______.
__________ separate the various colors of light, allowing astronomers to determine stellar composition and many other stellar properties.
The twin 10-m Keck telescopes can work together to obtain better angular resolution through a technique known as __________.
The Chandra X-ray observatory focuses X rays with __________ mirrors.
A 10-meter telescope has a larger ________ than a 4-meter telescope.
Galileo's telescope designs using lenses were examples of ___________.
Thermal radiation is defined as _________.
radiation with a spectrum whose shape depends only on the temperature of the emitting object
Compared to an atom as a whole, an atomic nucleus:
is very tiny but has most of the mass.
The spectra of most galaxies show redshifts. This means that their spectral lines _________.
have wavelengths that are longer than normal
Which of the following statements best describes the two principle advantages of telescopes over eyes?
Telescopes can collect far more light with far better angular resolution.
Some nitrogen atoms have seven neutrons and some have eight neutrons; these two forms of nitrogen are:
isotopes of each other.
How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?
What are the two most important properties of a telescope?
How much more light does an 8-meter telescope gather than a 2-meter telescope?
16 times as much
Suppose that two stars are separated in the sky by 0.01 arcsecond, and you observe them with a telescope that has an angular resolution of 1 arcsecond. What will you see?
The light from the two stars will be blended together so that they look like one star.
Match the words at the left to the correct blanks in the sentences at right.
A camera is an example of an instrument used for -imaging- observations.
-Spectroscopy- refers to telescopic observations in which we separate an object's light so we can measure its intensity at different wavelengths.
If we want to confirm that a star's brightness alternately dims and brightens, we need -time monitoring- observations of the star.
The familiar twinkling of the stars is caused by -atmospheric turbulence,- which also blurs telescopic images.
Human civilization is responsible for what astronomers call -light pollution-.
Why is a sunflower yellow?
it reflect yellow light
Which of the following procedures would allow you to make a spectrum of the Sun similar to the one shown, though with less detail?
Pass a narrow beam of sunlight through a prism.
In the illustration of the solar spectrum, the upper left portion of the spectrum shows the __________ visible light.
Which of the following best describes why the Sun's spectrum contains black lines over an underlying rainbow?
The Sun's hot interior produces a continuous rainbow of color, but cooler gas at the surface absorbs light at particular wavelengths.
Notice that the Sun's spectrum appears brightest (or most intense) in the yellow-green region. This fact tells us __________.
the approximate temperature of the Sun's surface
Suppose we want to know what the Sun is made of. What should we do?
Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory.
Any spectrum can be displayed either in photographic form as shown to the left or as a graph. Which of the following graphs could represent a portion of the Sun's visible light spectrum?
The smooth part of the curve represents the graph of the background rainbow of color; the dips in the curve represent the black lines where light is missing from the rainbow.
the arc with the dips picture
According to the laws of thermal radiation, hotter objects emit photons with _________.
a shorter average wavelength
Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?
its wavelength and energy
The set of spectral lines that we see in a star's spectrum depends on the star's:
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