Download Assignment 4A

Assignment 4A
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. Which of the following statements about the nucleus of a typical atom (such as the carbon in your little finger) is FALSE:
a. the nucleus has an overall positive charge
b. the nucleus takes up a very small amount of space compared to the entire atom
c. the nucleus contains both protons and neutrons
d. the nucleus repels the electrons which move around it
e. the nucleus contains most of the mass of the atom
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2. In the 19th century, it became clear that magnetism was not a separate force, but was always produced by the action of
a. electric charges that were in motion
b. the gravitational pull of the Earth
c. the strong nuclear force acting on electrons
d. light moving through a vacuum
e. rubbing a boy scout and a girl scout together to produce a fire
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3. Which of the following statements about electromagnetic radiation is FALSE?
a. it always spreads out at the speed of light
b. it is given off by all objects that are not at a temperature of absolute zero
c. it is typically produced when charged particles oscillate
d. different waves of electromagnetic radiation differ in their wavelength or frequency
e. it consists of charged particles given off by the nuclei of atoms
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4. The scientist who worked out the mathematics of the connections between electricity, magnetism, and light in the 19th century was:
a. Albert Einstein
b. James Clerk Maxwell
c. Isaac Newton
d. Wilhelm Wien
e. Ludwig Boltzmann
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5. Consider a radio wave from the transmitter of your favorite radio station, which has just reached the antenna of the radio in your room. Which of the following statements about this radio wave is CORRECT?
a. it has a frequency very close to the highest possible frequency for electromagnetic waves
b. it traveled between the transmitter and your radio's antenna at the speed of sound
c. its wavelength is much longer than the wavelength of the light you see reflected from the page of this assignment
d. the wave was originally produced by electrons that were not moving (at rest) inside the transmitter
e. the reason that it could reach your radio is because all of space is filled with a medium called the aether in which electromagnetic waves can vibrate
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6. Which of the following has the longest wavelength?
a. radio
b. visible light
c. ultraviolet
d. x­rays
e. you can't fool me, all these have the same wavelength
____
7. Which of the following travels through space the fastest?
a. light
b. radio waves
c. infrared
d. x­rays
e. you can't fool me, all of these travel through space at the same speed
____
8. The fastest speed in the universe is:
a. the speed of sound
b. the speed of light
c. the speed of electron oscillations
d. the speed with which Mercury orbits the Sun
e. the speed with which weekends seem to pass
____
9. The light which allows you to see this very interesting assignment is made up of waves. In these waves, the distance between crests is called the:
a. frequency
b. velocity
c. wavelength
d. amplitude
e. you can't fool me; in these waves, the distance between crests is zero
____ 10. Which of the following has the highest frequency?
a. visible light
b. gamma rays
c. radio waves
d. ultraviolet
e. you can't fool me, all these have the same frequency
____ 11. A Hertz is
a. a unit of wavelength
b. a unit of frequency
c. a unit of velocity
d. a unit of loudness
e. a well­known car­rental company
____ 12. A fashion designer decides to bring out a new line of clothing which reflects the longest wavelength of visible light. These articles of clothing will be what color to the human eye?
a. yellow­green
b. blue
c. violet
d. red
e. black
____ 13. Which of the following statements about photons is FALSE?
a. photons always travel at the speed of light
b. photons each carry a specific amount of energy
c. a photon of light cannot pass through the atmosphere of the Earth, and thus cannot be seen at the Earth's surface
d. high energy photons have a high frequency
e. a gamma­ray photon is more energetic than a visible light photon
____ 14. After a nice dinner around the campfire on a camping trip, you and a friend decide to get away from the fire to observe the stars. As you get farther and farther away, you see the brightness of the fire:
a. increase with distance
b. remain the same
c. decrease as the distance squared
d. change more and more in color (becoming redder)
e. this can't be answered without having more information
____ 15. 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. x­rays
b. gamma rays
c. infrared waves
d. ultraviolet waves
e. radio waves of the wavelength that carry FM broadcasts
____ 16. Human eyes evolved to detect visible light because:
a. it is the lowest energy band of the electromagnetic spectrum and thus easiest to detect
b. it is the only kind of radiation that penetrates the Earth's atmosphere at all
c. it is the band of the spectrum which is the least Doppler shifted coming from the Sun
d. it is the band of the spectrum where the Sun puts out the most energy
e. it is the band of the spectrum where the warm Earth glows the most effectively at night
____ 17. Which of the following statements about infrared radiation is TRUE?
a. it is the band of the electromagnetic spectrum where each wave or photon has the greatest energy
b. the wavelengths fall between radio waves and visible light on the electromagnetic spectrum
c. unlike light, infrared can never travel as fast as the speed of light
d. while many stars give off infrared, there is nothing on Earth at the right temperature to emit it
e. it is the radiation responsible for giving sunburns (or in large doses, skin cancer)
____ 18. Which of the following is not a type of radio wave?
a. microwaves
b. radar waves
c. the waves that carry AM or FM broadcasts
d. the sound waves coming from your transistor radio
e. the waves that carry television transmissions
____ 19. (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 mass
b. their temperature
c. their overall motion
d. their chemical makeup
e. their size
____ 20. The energy of random atomic and molecular motion is called
a. heat
b. the Doppler shift
c. spectroscopy
d. velocity
e. rock and roll
____ 21. Which of the following has the greatest average energy of random atomic and molecular motion?
a. a cube of ice
b. a cube of water
c. a cube of steam
d. a cube of air (on Earth)
e. a cube of the Sun
____ 22. An idealized object that does not reflect or scatter any radiation, but simply absorbs and re­emits every bit of radiation that falls on it is called:
a. a Doppler surface
b. an electromagnetic radiator
c. a blackbody
d. a spectrum
e. a vice president
____ 23. Two stars are giving off electromagnetic radiation. The hotter star will:
a. give off more radiation at all wavelengths
b. will have a higher average frequency of radiation
c. will radiate energy at more than one wavelength
d. will give off a continuous spectrum of waves
e. all of the above
____ 24. An astronomer discovers a new star and wants to measure its temperature. She would do this by:
a. measuring the Doppler shift of its spectral lines
b. making a blackbody curve and finding the wavelength of the peak (maximum)
c. measuring the intensity of radio waves the star gives off
d. measuring how much light the star reflects
e. sending a graduate student with a very long (and durable) thermometer to the star's vicinity
____ 25. When white light passes from the air into a different medium such as glass, it:
a. is dispersed into different colors
b. is reflected backwards
c. is refracted (bent)
d. is Doppler shifted
e. more than one of the above
____ 26. 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. roughly the same amount of energy as the second
c. half as much energy as the second
d. about 16 times the energy of the second
e. this problem cannot be solved with just the information we were given
____ 27. Which of the following is NOT done best with a spectrometer?
a. measuring how bright sources of light in the universe appear
b. measuring the different colors in the spectrum
c. measuring the amount that lines are Doppler shifted
d. measuring what elements are present in a star
e. measuring what conditions are like in the cool atmosphere of a star
____ 28. 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. a continuous spectrum
b. an absorption spectrum
c. an emission spectrum
d. a Doppler shift
e. all of the above
____ 29. Astronomers observe a typical star using a telescope and a spectrometer (one of various devices to produce a spectrum). They will see:
a. a continuous spectrum
b. an absorption spectrum
c. an emission spectrum
d. a Doppler shift
e. more than one of the above
____ 30. If I were to scale up an atom until it were the size of a sports arena, the space filled by the positive charges inside the atom (according to the work of Ernest Rutherford early in this century) would be:
a. as big as the entire stadium (and very thinly spread out)
b. as big as the space filled by all the negative charges (that's why the atom is neutral)
c. very small (perhaps the size of a soccer ball) and in the middle
d. an extremely thin layer spread completely around the outer walls of the stadium
e. this question cannot be answered (even roughly) without knowing which kind of atom we are discussing
____ 31. Atoms typically consist of electrons, protons, and neutrons. The most common isotope of one element, however, only has two of these three types of particles. This element is:
a. helium
b. hydrogen
c. uranium
d. carbon
e. silicon
____ 32. Two versions of an element with different numbers of neutrons are called:
a. molecules
b. electron pairs
c. isotopes
d. ions
e. re­runs
____ 33. Why do different types of atoms (elements) give off or absorb different spectral lines?
a. all elements have the same lines, but they are Doppler shifted by different amounts
b. in some elements, electrons can only move to odd numbered levels, in others only to even numbered ones
c. in heavier elements, diffraction spreads out the lines that the atom produces, making the colors different
d. because the spacing of the energy levels is different in different atoms
e. because some atoms do not have a ground state, while others have three or four
____ 34. The idea that atoms radiate energy only when their electrons move from higher to lower energy levels was first advanced by:
a. J. J. Thomson
b. Niels Bohr
c. Ernest Rutherford
d. Albert Einstein
e. Christian Doppler
____ 35. When an atom has lost one or more electrons, it is said to be:
a. ionized
b. excited
c. in its ground state
d. red shifted
e. over the hill
____ 36. What happens as an electron falls from a higher level to a lower level in an atom?
a. a photon is given off
b. the color of the wave involved shifts to the red
c. a photon is absorbed
d. another electron from the lower level takes its place
e. nothing happens; electrons can only go from a lower level to a higher level
____ 37. How do astronomers learn what elements are present in a given star?
a. look at what color light dominates its continuous spectrum
b. listen for coded signals in the radio waves it gives off in the FM band
c. look at the absorption lines in its spectrum
d. send spacecraft like Voyager to examine its make­up from close­up
e. compare visible­light photographs of the star (taken with large telescopes) to those of the Sun.
____ 38. Planck's constant relates:
a. the energy of a wave to the number of protons in the nucleus of the atom that emitted it
b. the frequency of a wave to its energy
c. the maximum energy emitted by a blackbody to its temperature
d. the energy emitted by a star to its temperature
e. the Doppler shift of a light source to its speed
____ 39. Which of the following consists of electromagnetic waves with the shortest wavelength?
a. a beam of green light
b. TV transmissions bringing us Monday night football
c. the sound of the instructor's voice
d. the waves of a dental x­ray
e. the rays that tan a sunbather on the beach
____ 40. 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. visible light
b. infra­red
c. ultra­violet
d. black light
e. no telescope will be effective if I am in a dark room
____ 41. 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 clear). What wavelength of electromagnetic radiation would I be smartest to use:
a. visible light
b. x­rays
c. radar waves
d. ultra­violet
e. none would work
____ 42. The two regions of the electromagnetic spectrum where the Earth's atmosphere is transparent (radiation can get in) are visible light and:
a. ultraviolet
b. x­rays
c. some radio waves
d. gamma­rays
e. you can't fool me, the atmosphere is transparent ONLY for visible light
____ 43. A local radio station broadcasts your favorite radio program at frequency f = 97.2 MHz. The wavelength of this frequency of electromagnetic radiation is
a. 3 x 108 m
b. 309 m
c. 3.09 m
d. 9.72 m
e. none of the above
____ 44. Given that the observed wavelength of a radiating object is = 150 nm, what is its frequency?
a. f = 3 x 1014 Hz
b. f = 2 x 1015 Hz
c. f = 3 x 108 nm
d. f = 3 x 108 Hz
e. none of the above
____ 45. What is the energy in joules of a photon with a frequency of 2 x 1015 waves per second? Hint: h 6.63 x 10–34 J∙s)
a. 133 J
b. 1.33 x 10–11 J
c. 1.33 x 10–18 J
d. 6.63 x 1018 J
e. You can’t fool me, this photon has zero energy.
____ 46. Two stars with the same size in diameter have temperatures T1 = 5800 K and T2 = 2900 K, respectively, which star is brighter and how many times brighter? (Hint: Flux is a measure of brightness)
a. Star with T2 is 2 times brighter than star with T1
b. Star with T1 is 8 times brighter than star with T2
c. Star with T1 is 16 times brighter than star with T2
d. Star with T2 is just as bright as star with T1
e. Star with T2 is 16 times brighter than star with T1
____ 47. An object radiates like a blackbody and emits most of its radiation at wavelength max = 50,000 nm. What is the object’s temperature in Kelvins.
a. 6 K
b. 50,000 K
c. 3 K
d. 60 K
e. none of the above
____ 48. An astronomer observes a spectral emission line from a galaxy at a wavelength of 600 nm. This same spectral line is measured in the lab (or stationary) at a wavelength of 500 nm. What is the velocity of the galaxy toward or away from Earth in units of the speed of light c?
a. 0.2 c moving away from Earth
b. 0.2 c moving toward Earth
c. 0.9 c moving away from Earth
d. c = 3 x 108 m/s moving toward Earth
e. none of the above
Assignment 4A
Answer Section
MULTIPLE CHOICE
1. ANS: D
3. ANS: E
5. ANS: C
7. ANS: E
9. ANS: C
11. ANS: B
13. ANS: C
15. ANS: E
17. ANS: B
19. ANS: B
21. ANS: E
23. ANS: E
25. ANS: E
27. ANS: A
29. ANS: E
31. ANS: B
33. ANS: D
35. ANS: A
37. ANS: C
39. ANS: D
41. ANS: C
43. ANS: C
45. ANS: C
47. ANS: D