Upgrade to remove ads
The Essential Cosmic Perspective: Chapter 5: Light
Terms in this set (61)
The wavelength of a wave is
the distance between two adjacent peaks of the wave.
How are wavelength, frequency, and energy related for photons of light?
Longer wavelength means lower frequency and lower energy.
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
radio, infrared, visible light, ultraviolet, X rays, gamma rays
How many atoms fit across the period at the end of this sentence?
Compared to the size of its nucleus, the size of an atom is about
100,000 times greater
Which of the following statements about electrical charge is true?
A positive charge and a negative charge will attract each other.
Which of the following statements about electrons is not true?
Electrons orbit the nucleus rather like planets orbiting the Sun
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic mass number?
The atomic number is 79, and the atomic mass number is 197.
An atom of the element iron has an atomic number of 26 and an atomic mass number of 56. If it is neutral, how many protons, neutrons, and electrons does it have?
26 protons, 30 neutrons, 26 electrons
When an atom loses an electron, it becomes
An electron-volt is
an amount of energy much smaller than a joule.
How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
It releases a photon equal in energy to its own energy drop.
If a material is transparent, then it
transmits light well
Everything looks red through a red filter because
the filter transmits red light and absorbs other colors.
Which of the following statements about X rays and radio waves is not true?
X rays travel through space faster than radio waves.
We can see each other in the classroom right now because we
reflect visible light
Without telescopes or other aid, we can look up and see the Moon in the night sky because it
reflects visible light
If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels the gas produces
an emission line spectrum
When an electron in an atom goes from a higher energy state to a lower energy state, the atom
emits a photon of a specific frequency.
Spectra from neutral atoms compared with spectra from ionized atoms of the same element
have different sets of spectral lines.
Which of the following objects is not a close approximation of a thermal emitter?
hot, thin gas
Which of the following statements about thermal radiation is always true?
A hot object emits photons with a higher average energy than a cool object.
A gas heated to millions of degrees would emit
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?
The star is moving toward us.
If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
The planet is rotating.
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
The blue star has a hotter surface temperature than the red star.
Which of the following is least reasonable regarding our perception of color?
A banana which appears yellow in white light would appear blue when illuminated by blue light.
Currently, the largest optical telescope mirrors have a diameter of
Which of the following is not a good reason to place observatories on remote mountain tops?
to be able to observe at radio wavelengths
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Photons of different energy behave differently and require different collection strategies
The largest effective telescope, created by radio interferometry, is the size of
Which of the following wavelength regions cannot be studied with telescopes on the ground?
x rays and ultraviolet
In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?
In what wavelength range was interferometry first routinely used?
What is the angular resolution of the human eye?
about 1 arcminute, or 1/60 of a degree
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.
What do astronomers mean by light pollution?
Light pollution refers to lights from human sources that make it difficult to see the stars at night.
The stars in our sky twinkle in brightness and color because of
turbulence in the Earth's atmosphere
What is the purpose of adaptive optics?
It reduces blurring caused by atmospheric turbulence for telescopes on the ground.
What is the purpose of interferometry?
It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.
Which of the following best describes why we say that light is an electromagnetic wave?
The passage of a light wave can cause electrically charged particles to move up and down.
Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?
Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons
Suppose you built a scale-model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend?
Which of the following statements is true of green grass?
It absorbs red light and reflects green light.
Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?
The cloud is cool and lies between you and a hot star.
The following diagram represents energy levels in a hydrogen atom. The labeled transitions (A through E) represent an electron moving between energy levels.Which labeled transition represents an electron that absorbs a photon with 10.2 eV of energy and how much more energy would this electron need to absorb to become completely dislodged from the atom (ionization)?
If an electron at level 1 in a hydrogen atom absorbs 10.2 eV of energy, it moves to level 2. What typically happens next?
The electron returns to level 1 by emitting an ultraviolet photon with 10.2 eV of energy.
Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?
Its surface is cooler than the surface of the Sun.
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 486.0 nm. What can we conclude?
The star is moving toward us.
Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?
Star X is moving away from us faster than Star Y.
Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which one?
The total amount of light in the spectrum tells us the star's radius.
Suppose that the angular separation of two stars is 0.1 arcsecond, and you photograph them with a telescope that has an angular resolution of 1 arcsecond. How will the stars appear in the photograph?
The two stars will look like a single point of light.
How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?
The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
It is closer to the stars.
The Chandra X-ray Observatory must operate in space because
X rays do not penetrate Earth's atmosphere.
Which of the following is always true about images captured with X-ray telescopes?
They are always displayed in false color.
According to Wien's Law, if the surface temperature is increased by a factor of 2, its peak wavelength will
decrease by a factor of 2
What is spectroscopy?
the study of the properties of light that depend on wavelength
Typical stellar spectra appear as:
a rainbow with some dark lines mixed in
Which of these produces the classic continuous spectrum?
an incandescent light bulb
Which of the following is least reasonable regarding cosmic background radiation (CBR)?
Data for CBR is collected by pointing telescopes into dark regions of the sky (that do not appear to have any bright objects).
Sets found in the same folder
The Essential Cosmic Perspective Chapter 4
The Essential Cosmic Perspective Chapter 3
The Essential Cosmic Perspective: Chapter 2
The Essential Cosmic Perspective: Chapter 1
Sets with similar terms
module 3 quiz
Astronomy Chapter 5
Mastering Astronomy Chapter 5
Astro Ch 5
Other sets by this creator
Astonomy Chapter 9
Astronomy Chapter 6/10
Astronomy Chapter 1
Other Quizlet sets
biology I: ch. 3 organic chemistry notes
feminist therapy quiz
AP Government chap.4 key cases
Dr Reed Mech Vent Chapter 4