light

Why is an absorption spectrum especially useful for astronomers? a) It has dark lines in it that allow astronomers to determine what elements are in the star b) An absorption spectrum is not useful to astronomers at all. When they see one, it means they cannot learn anything about the stars that produced the annoying absorption. c) It shows that the stars are transparent; we can see right through them d) It has bright lines in it which allow astronomers to determine how bright the star is e) It helped astronomers to understand the rainbows we see on Earth after storms

a) It has dark lines in it that allow astronomers to determine what elements are in the star

An artist who likes working with sources of light decides to make a modern sculpture out of electrified glass tubes that contain very thin (rarified) neon gas. When the sculpture is finished, and the electricity is turned on, the tubes glow with a rich red color. What we are seeing is: a) an emission spectrum b) an absorption spectrum c) all of the above d) a continuous spectrum e) a Doppler shift

a) an emission spectrum

We have two waves of light, A and B. Wave A has a higher frequency than wave B. Then wave B must have a) longer wavelength b) higher speed c) lower speed d) this can't be determined from the information given e) shorter wavelength

a) longer wavelength

I want to examine the surface of a planet that is covered by a thick atmosphere (which includes oxygen and contains a very thick layer of water clouds that never clears). What wavelength of electromagnetic radiation would I be smartest to use: a) radar waves b) none would work c) x-rays d) ultra-violet e) visible light

a) radar waves

Not all wavelengths of electromagnetic radiation can penetrate the Earth's atmosphere. Of the following types of waves that come from space, which one are you likely to be able to detect most easily from our planet's surface: a) radio waves of the wavelength that carry FM broadcasts b) gamma rays c) infrared waves d) x-rays e) ultraviolet waves

a) radio waves of the wavelength that carry FM broadcasts

Wien's Law relates the wavelength at which a star gives off the greatest amount of energy to the star's a) temperature b) overall color c) none of the above d) motion toward us or away from us e) magnetic field

a) temperature

Most ultraviolet radiation does not penetrate to the Earth's surface. Instead it is absorbed in: a) the ozone layer b) the region between the Earth and the Sun c) stratosphere d) the ionosphere

a) the ozone layer

The light which allows you to see this very interesting exam is made up of waves. In these waves, the distance between crests is called the a) wavelength b) you can't fool me; in these waves, the distance between crests is zero c) frequency d) velocity e) amplitude

a) wavelength

In the future, several students living on board a space station decide to have a race among different types of electromagnetic radiation. Which of the following travels through space the fastest? a) you can't fool me, all of these travel through space at the same speed b) x-rays c) radio waves d) infrared e) visible light

a) you can't fool me, all of these travel through space at the same speed

An idealized object that does not reflect or scatter any radiation that hits it, but simply absorbs every bit of radiation that falls on it is called: a) a spectrum b) a blackbody c) a doppler surface d) an electromagnetic radiator

b) a blackbody

A Hertz is a) a unit of velocity b) a unit of frequency c) a unit of loudness d) a unit of wavelength

b) a unit of frequency

How do astronomers learn what elements are present in a given star? a) compare visible-light photographs of the star (taken with large telescopes) to those of the Sun. b) look at the absorption lines in its spectrum c) listen for coded signals in the radio waves it gives off in the FM band d) look at what color light dominates its continuous spectrum e) send spacecraft like Voyager to examine its make-up from close-up

b) look at the absorption lines in its spectrum

Astronomers observe a typical star using a telescope and a spectrometer. They will see: a) a Doppler shift b) more than one of the above c) an emission spectrum d) a continuous spectrum an absorption spectrum

b) more than one of the above

The Stefan-Boltzmann Law relates the energy flux coming from a blackbody (such as a star) to its: a) wavelength where maximum energy is emitted b) temperature c) overall color d) atomic ground state e) none of the above

b) temperature

We observe a glowing cloud of gas in space with a spectroscope. We note that many of the familiar lines of hydrogen that we know on Earth seem to be in a different place. They are shifted toward the blue or violet end of the spectrum compared to their positions in the spectrum of glowing hydrogen gas on Earth. From this we can conclude that: a) the cloud is much cooler than hydrogen on Earth b) the cloud is moving toward us c) the cloud is much hotter than hydrogen on Earth d) the cloud is moving away from us e) none of the above can be concluded from this observation

b) the cloud is moving toward us

(In the absence of a strong magnetic field), what is the chief factor that determines what type of electromagnetic radiation objects give off: a) their chemical makeup b) their temperature c) their size d) their distance from the Earth's e) center e) their mass

b) their temperature

How fast do electro-magnetic waves travel? a) at the speed of charge b) at the speed of sound c) at the speed of light d) they always have zero e) at different speeds, depending on the temp of atoms that produce them

c) at the speed of light

Why do different types of atoms (elements) give off or absorb different spectral lines? a) in heavier elements, diffraction spreads out the lines that the atom produces, making the colors different b) in some elements, electrons can only move to odd numbered levels, in others only to even numbered ones c) because the spacing of the energy levels is different in different atoms d) because some atoms do not have a ground state, while others have three or four e) all elements have the same lines, but they are Doppler shifted by different amounts

c) because the spacing of the energy levels is different in different atoms

The energy of random atomic and molecular motion is called a) reflection b) the doppler shift c) heat d) spectra

c) heat

You are alone in a large, completely dark auditorium on Earth. What kind of telescope should I use from the other side of the auditorium to detect the electromagnetic radiation emitted by your body? a) ultra-violet b) no telescope will be effective if I am in a dark room c) infra-red d) black light e) visible light

c) infra-red

Which of the following has the longest wavelength? a) visible light waves b) you can't fool me, all these have the same wavelength c) radio waves d) ultraviolet waves e) x-rays

c) radio waves

The fastest speed in the universe is a) the speed with which weekends seem to pass b) the speed of sound c) the speed of light d) the speed of electron oscillations e) the speed with which mercury orbits the sun

c) the speed of light

An astronomer observes two ordinary stars. The first one turns out to be twice as hot as the second. This means that the first one radiates: a) twice as much energy as the second b) this problem cannot be solved with just the information we were given c) roughly the same amount of energy as the second d) about 16 times the energy of the second e) half as much energy as the second

d) about 16 times the energy of the second

To go from a lower level in an atom to a higher level, an electron must a) give off a photon of energy b) lose its electric charge c) wait until the atom has changed into another atom with more protons d) absorb a photon of energy

d) absorb a photon of energy

The fact that each type of atom has a unique pattern of electron orbits helps explain why a) astronomers have not been able to figure out what atoms stars are made of b) most atoms don't have a ground state c) each type of atom contains different numbers of neutrons d) each type of atom shows different absorption or emission spectra e) some atoms don't have any isotopes

d) each type of atom shows different absorption or emission spectra

Which of the following has the highest frequency? a) visible light b) radio waves c) you can't fool me, all these have the same frequency d) gamma rays e) ultraviolet waves

d) gamma rays

When a star or galaxy is moving away from us, we observe the Doppler effect by seeing the lines in its spectrum a) yellow-shifted (shifted so all the colors become a little bit yellower) b) become darker and darker (like a blackbody) c) you can't fool me, the Doppler effect only applies to motions on Earth, not to the motions of the stars and galaxies d) red-shifted (shifted toward the red end of the light spectrum) e) blue-shifted (shifted toward the blue or violet end of the light spectrum)

d) red-shifted (shifted toward the red end of the light spectrum)

Two stars have the same diameter and are at the same distance from us (but in different parts of the sky.) Star A has a temperature of 4000 K, while star B has a temperature of 8000K. Which of the following statements is true: a) the two stars have the same total energy flux (luminosity) b) star B has one half the energy flux (luminosity) that star A has c) Sorry, professor, we don't have enough information to compare the energy flux (luminosity) of the two stars d) star B has 16 times the energy flux (luminosity) that star A has e) star B has twice the energy flux (luminosity) that star A has

d) star B has 16 times the energy flux (luminosity) that star A has

Which of the following statements about electromagnetic radiation is FALSE? a) it always spread out at the speed of light b) it is given off by all objects that are not at a temperature of absolute zero c) different waves of electromagnetic radiation differ in their wavelength or frequency d) the radiation consists of tiny charged particles given off by the nuclei of atoms

d) the radiation consists of tiny charged particles given off by the nuclei of atoms

What happens as an electron falls from a higher level to a lower level in an atom? a) another electron from the lower level takes its place b) a photon is absorbed c) nothing happens; electrons can only go from a lower level to a higher level d) the color of the wave involved shifts to the red e) a photon is given off

e) a photon is given off

We discussed that light sometimes acts like a photon. What is a photon? a) a charged particle in the nucleus of every atom b) a kind of magnetic substance found in reflective minerals c) you can't fool me. Einstein showed that photons were a mistake - they don't exist d) a kind of sound that is too high frequency for the human ear to hear e) a self-contained "packet" of electro-magnetic energy

e) a self-contained "packet" of electro-magnetic energy

An astronomer discovers a new star and wants to measure its temperature. She would typically do this by: a) measuring the intensity of radio waves the star gives off b) measuring how much light the star reflects c) sending a graduate student with a very long (and durable) thermometer to the star's vicinity d) measuring the Doppler shift of its spectral lines e) making a blackbody curve and finding the wavelength of the peak (maximum)

e) making a blackbody curve and finding the wavelength of the peak (maximum)

Which of the following statements about photons is FALSE? a) high energy photons have a high frequency (when thought of as waves) b) photons always travel at the speed of light c) photons each carry a specific amount of energy d) a gamma-ray photon carries more energy than a visible light photon e) photon of visible light cannot pass through the atmosphere of the Earth, and thus cannot be seen at the Earth's surface

e) photon of visible light cannot pass through the atmosphere of the Earth, and thus cannot be seen at the Earth's surface

A fashion designer decides to bring out a new line of clothing which reflects the longest wavelength of visible light. What color will these articles of clothing be to the human eye? a) violet b) blue c) black d) yellow-green e) red

e) red