Study Questions - Set 2A
Chapter 5
1. In 1675, Romer measured the speed of light by
A.timing eclipses of Jupiter's satellites, which appeared to occur later when Earth was farther from Jupiter.
B.measuring how long it took the light from stars located at different distances to reach Earth.
C.reflecting light from a mirror rotating at a known speed and measuring the angle of deflection of the light beam.
D.opening a shutter on a lantern on a hilltop and measuring the time taken for light from an assistance's shuttered lantern to return.


2. The speed of light in space is
A.very large, but not infinite: 3 × 1010 meters per second.
B.very large, 3 × 108 meters per second, independent of the speed of its source.
C.infinite, traveling through space instantaneously.
D.variable, depending on the speed of its source, but very large (on average, 3 × 108 meters per second).


3. When light passes through a prism of glass, the
A.different colors are caused by multiple reflections in the prism and interference between the resulting beams.
B.prism absorbs colors from different parts of the broad beam coming out of the prism, leaving the complementary colors that we see.
C.prism adds colors to different parts of the broadly scattered beam coming out of it.
D.different colors or wavelengths of light are separated in angle by the prism.


4. Around 1801, Thomas Young in England showed that light behaves as a wave by
A.deriving a set of mathematical equations that described electromagnetic waves that could have different wavelengths.
B.shining light through two closely spaced slits and observing the resulting pattern of light on a white screen.
C.reflecting light from a rotating mirror and measuring the deflection in different directions.
D.shining light through a glass prism and observing the resulting pattern of colors on a white screen.


5. An electrical spark, such as lightning, generates electromagnetic radiations over a wide range of wavelengths. How much longer does a pulse of radio energy take to travel between two detector stations 100 m apart than a pulse of ultraviolet radiation from the same spark?
A.much longer, since radio waves have much longer wavelengths and therefore travel slower
B.much shorter, since long-wavelength radiations travel faster
C.just a little longer, since the high-frequency UV radiation travels faster than the low-frequency radio waves
D.The time is identical, since both pulses travel at the speed of light.


6. Visible light occupies which position in the whole electromagnetic spectrum?
A.between radio and infrared radiation
B.between ultraviolet and X rays
C.between infrared and ultraviolet
D.between infrared and microwave


7. Which one of the following statements is true?
A.Visible light takes up only a very small part of the total range of wavelengths in the electromagnetic spectrum.
B.Visible light takes up most (but not all) of the total range of wavelengths in the electromagnetic spectrum.
C.Visible light takes up all of the electromagnetic spectrum.
D.Visible light is not part of the electromagnetic spectrum.


8. Violet light differs from red light in that violet light
A.has a longer wavelength than red light.
B.travels more slowly (through a vacuum) than red light.
C.travels more quickly (through a vacuum) than red light.
D.has a shorter wavelength than red light.


9. In terms of wavelengths, gamma rays are
A.the shortest-wavelength electromagnetic waves.
B.intermediate between radio and infrared waves.
C.intermediate between X rays and ultraviolet waves.
D.the longest-wavelength electromagnetic waves.


10. The temperature of a gas cloud in space is directly related to and representative of the
A.number of atomic collisions per second within the cloud.
B.average speed of its atoms.
C.density of the cloud.
D.color of the cloud.


11. A blackbody is an idealized object that
A.reflects and emits light with the same intensity at all wavelengths.
B.neither reflects nor emits light.
C.both reflects and emits light in a manner determined by its temperature.
D.reflects no light and emits light in a manner determined by its temperature.


12. If all stars are considered to be perfect blackbodies, then it should follow that all stars
A.of the same composition (made of exactly the same material) emit the same energy flux.
B.of the same size emit the same energy flux.
C.traveling at the same speed emit the same energy flux.
D.of the same temperature emit the same energy flux.


13. As a newly formed star continues to contract, its temperature increases while the chemical nature of the gas does not change. What happens to the peak wavelength of its emitted radiation?
A.It moves toward shorter wavelengths (e.g., IR to visible).
B.It moves toward longer wavelengths (e.g., visible to IR).
C.It remains constant, since the chemical state of the gas does not change.
D.It does not change, since it does not depend on temperature.


14. The energy flux F from a star is the
A.amount of visible light energy emitted by each square meter of the star's surface each second.
B.amount of energy emitted by each square meter of the star's surface each second.
C.total energy emitted by the star over its lifetime.
D.amount of energy emitted by the entire star each second.


15. A piece of iron is heated from 400 to 800 K (127 to 527°C). By what factor will the total energy per second emitted by this iron increase?
A.2
B.296.5
C.4
D.16


16. The hot, dense gas existing in the Sun emits energy
A.at all wavelengths uniformly.
B.at all wavelengths, with a peak at one particular wavelength (color).
C.only at certain wavelengths and no others.
D.mostly at the longest and shortest wavelengths, less in between.


17. In its interaction with matter, light behaves
A.only as waves.
B.alternatively as particles or as waves, switching its properties about once every second.
C.as both waves and particles, depending on the type of interaction.
D.only as small particles, photons.


18. If two photons in a vacuum have different energies, what can we say about the wavelengths of these photons?
A.The wavelength depends only on color, not on energy.
B.The higher-energy photon has the shorter wavelength.
C.They have the same wavelength; all photons have the same wavelength, regardless of energy.
D.The higher-energy photon has the longer wavelength.


19. The early workers in spectroscopy (Fraunhofer with the solar spectrum, Bunsen and Kirchhoff with laboratory spectra) discovered which very significant fact about the spectra produced by hot gases, such as elements heated in a flame?
A.The higher the temperature, the greater the red shift of the emitted spectral lines.
B.They produce their own characteristic pattern of spectral lines, which remain fixed as the temperature increases.
C.They emit spectral lines that move continuously toward the blue end of the spectrum as the gas temperature increases.
D.They produce the same set of spectral lines and are hence indistinguishable.


20. Atoms in a thin, hot gas (such as a neon advertising sign) emit light at
A.specific wavelengths, depending on the element.
B.all wavelengths, with the shape of the continuum distribution depending on the temperature of the gas.
C.only visible wavelengths.
D.only a specific single wavelength.


21. The dark absorption lines in the solar spectrum are caused by absorption
A.of sunlight in a layer of pure hydrogen gas overlying the solar surface.
B.of sunlight in a cooler layer of gas overlying the hot solar surface.
C.entirely by atoms and molecules in Earth's cool atmosphere.
D.of sunlight in a hotter layer of gas overlying the cooler solar surface.


22. Why is the sky blue?
A.The air molecules absorb red light better than blue light, allowing more blue light to reach our eyes.
B.The air molecules scatter blue light better than red light, so more blue light reaches our eyes.
C.The air molecules scatter red light better than blue light, so less red light reaches our eyes.
D.The air molecules absorb blue light better than red light, making the sky appear bluer.


23. The basic makeup of an atom is
A.small, negatively charged particles orbiting around a central positive charge.
B.negative and positive charges mixed uniformly over the volume of the atom.
C.small, positively charged particles orbiting around a central negative charge.
D.miniature planets, possibly with miniature people, gravitationally bound in orbits around a miniature star.


24. The physical force that holds the components of an atom together is the
A.nuclear force from protons and neutrons.
B.centrifugal force on the electrons, caused by their orbital motion.
C.gravitational force between the nucleus and the electrons.
D.electromagnetic attraction between the nucleus and the electrons.


25. Most of the mass of ordinary matter resides in the
A.electrons and the nuclei, shared equally.
B.nuclei of atoms.
C.electron cloud around the nuclei of atoms.
D.energy stored within the atom in electromagnetic forces.


26. The property of an atom that uniquely defines how it behaves chemically and fixes its position in the periodic table is
A.the total number of protons and neutrons.
B.the number of neutrons in the nucleus.
C.its physical size.
D.the number of protons in the nucleus.


27. An atom that has had one or more electrons removed is known as
A.an ion.
B.a molecule.
C.an excited atom.
D.an isotope.


28. According to the Doppler effect,
A.the wavelength of light is shifted to a shorter wavelength if the source of light is moving toward you.
B.the wavelength of light is shifted to a longer wavelength if the source of the light is moving toward you.
C.the wavelength of peak emission of light from a source changes as the temperature of the source changes.
D.spectral lines are split into two or more wavelengths when the source of the light is in a strong magnetic field.



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