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25 Cards in this Set
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If you have a 100-watt light bulb, how much energy does it use each minute? 600 watts 6,000 watts 600 joules 100 joules 6,000 joules |
6,000 joules |
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The frequency of a wave is the number of peaks passing by any point each second measured in cycles per second measured in hertz (Hz) equal to the speed of the wave divided by the wavelength of the wave all of the above |
all of the above |
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How are wavelength, frequency, and energy related for photons of light? Longer wavelength means higher frequency and lower energy. Longer wavelength means lower frequency and lower energy. There is no simple relationship because different photons travel at different speeds. Longer wavelength means lower frequency and higher energy. Longer wavelength means higher frequency and higher energy. |
Longer wavelength means lower frequency and lower energy |
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Which of the following statements about X rays and radio waves is not true? X rays have higher energy than radio waves. X rays have higher frequency than radio waves. X rays have shorter wavelengths than radio waves. X rays and radio waves are both forms of light, or electromagnetic radiation. X rays travel through space faster than radio waves. |
X rays travel through space faster than radio waves |
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An electron-volt is the energy of one electron. the energy jump between the first and second energy levels of hydrogen. an amount of energy much larger than a joule. an amount of energy much smaller than a joule. the charge of one electron. |
an amount of energy much smaller than a joule |
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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 absorption line spectrum. thermal radiation. radio waves. X rays. an emission line spectrum. |
an emission line spectrum |
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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. absorbs several photons of a specific frequency. can emit a photon of any frequency. absorbs a photon of a specific frequency. can absorb a photon of any frequency. |
emits a photon of a specific frequency |
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When white light passes through a cool cloud of gas, we see thermal radiation. an absorption line spectrum. visible light. an emission line spectrum. infrared light. |
an absorption line spectrum |
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Which of the following statements about thermal radiation is always true? A hot object emits more radio waves than a cool object. A hot object emits more X rays than a cool object. A hot object emits photons with a longer wavelength than a cool object. A hot object emits photons with a higher average energy than a cool object. |
A hot object emits photons with a higher average energy than a cool object |
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You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two? The line in the faster rotating star is redshifted. The line in the faster rotating star is narrower. There is no difference. The line in the faster rotating star is broader. The line in the faster rotating star is blueshifted. |
The line in the faster rotating star is broader |
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What is the difference between energy and power? Power is the rate at which energy is used, so its units are a unit of energy divided by a unit of time. Power is used to describe energy of light, while the term energy has a broader meaning. Power is measured in joules and energy is measured in watts. There's no difference: Energy and power are different names for the same thing. |
Power is the rate at which energy is used, so its units are a unit of energy divided by a unit of time. |
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Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon? its temperature. the chemical composition of the object that emitted it. its wavelength and energy. its acceleration. |
its wavelength and energy. |
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When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called_______. frequencies photons wavicles gamma rays |
photons |
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From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? radio, infrared, visible light, ultraviolet, X rays, gamma rays infrared, visible light, ultraviolet, X rays, gamma rays, radio gamma rays, X rays, ultraviolet, visible light, infrared, radio gamma rays, X rays, visible light, ultraviolet, infrared, radio |
gamma rays, X rays, ultraviolet, visible light, infrared, radio |
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Thermal radiation is defined as ________. radiation in the form of emission lines from an object. radiation with a spectrum whose shape depends only on the temperature of the emitting object. radiation produced by an extremely hot object. radiation that is felt as heat. |
radiation with a spectrum whose shape depends only on the temperature of the emitting object. |
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According to the laws of thermal radiation, hotter objects emit photons with ________. a shorter average wavelength. a lower average frequency. a lower average energy. a higher average speed. |
a shorter average wavelength. |
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Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you? The Doppler shift of the star's spectrum. Whether the star's spectrum has more emission lines or more absorption lines. The wavelengths of spectral lines in the star's spectrum. The peak energy of the star's thermal radiation. |
The wavelengths of spectral lines in the star's spectrum. |
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The spectra of most galaxies show redshifts. This means that their spectral lines ________. always are in the red part of the visible spectrum. have wavelengths that are longer than normal. have wavelengths that are shorter than normal. have a higher intensity in the red part of the spectrum. |
have wavelengths that are longer than normal. |
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Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude? The star is getting hotter. The star is moving away from us. The star is getting colder. The star is moving toward us. |
the star is moving toward us |
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In what part of the spectrum would you need to be able to see so that you could detect the light emitted by students in astronomy class? visible ultraviolet x-ray infrared |
infrared |
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You observe a distant galaxy. You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared. What do you conclude? he galaxy is moving toward you. The galaxy is moving away from you. The composition of the galaxy is changing. The galaxy is made purely of hydrogen. The galaxy has very weak gravity. |
The galaxy is moving away from you. |
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If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects? The one with the large redshift is moving away from us faster than the one with the small redshift. The one with the large redshift is moving away from us, and the one with the small redshift is moving toward us. The one with the large redshift is hotter and therefore is putting out more radiation. The one with the large redshift is redder than the other one. The one with the large redshift is moving toward us faster than the one with the small redshift. |
The one with the large redshift is moving away from us faster than the one with the small redshift. |
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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 red star has a hotter surface temperature than the blue star. The blue star is farther away than the red star. The blue star has a hotter surface temperature than the red star. The red star is more massive than the blue star. The blue star is more massive than the red star. |
The blue star has a hotter surface temperature than the red star. |
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You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two? There is no difference. The line in the faster rotating star is narrower. The line in the faster rotating star is broader. The line in the faster rotating star is blueshifted. The line in the faster rotating star is redshifted. |
The line in the faster rotating star is broader. |
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If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits 12 times more energy. 3 times more energy. 81 times more energy. 9 times more energy. Impossible to determine. |
81 times more energy. |
