Deck 30: Light Emission

Question 1

The energy of a photon is related to

A)the energy given to the atom that emits it.
B)the energy transition in de-excitation.
C)its frequency.
D)all of the above
E)none of the above

Answer 1

all of the above

Question 2

Green light emitted by excited mercury vapor corresponds to an energy transition in the mercury atom. A more energetic transition might emit

A)red light.
B)blue light.
C)white light.
D)any of these

Answer 2

blue light.

Question 3

A throbbing pulse of electromagnetic radiation is called a

A)proton.
B)photon.
C)phototron.
D)newtron.
E)nooytron.

Answer 3

photon.

Question 4

An atom that absorbs a certain amount of energy can then emit

A)only a photon of that energy.
B)a photon of any energy.
C)a photon of the same or higher energy.
D)a photon of the same or lower energy.

Question 5

Light from a lit match originates with accelerating

A)electrons.
B)protons.
C)neutrons.
D)all of the above

Question 6

The best visible safety light in the darkroom that will emit low-energy photons is

A)violet.
B)blue.
C)green.
D)any of the above
E)none of the above

Question 7

The energy per photon in ultraviolet light is greater than in

A)radio waves.
B)microwaves.
C)visible light.
D)all of the above
E)none of the above

Question 8

Which color of visible light carries the most energy per photon?

A)red
B)green
C)blue
D)violet
E)all the same

Question 9

Compared to the energy of a photon of red light, the energy of a photon of blue light is

A)less.
B)more.
C)the same.

Question 10

A radio wave and a visible light wave differ only in

A)frequency.
B)energy per photon.
C)both of these
D)none of these

Question 11

Electrons with greater potential energies relative to the atomic nucleus are

A)inner electrons.
B)outer electrons.
C)both the same

Question 12

Light is emitted when an electron

A)is boosted to a higher energy level.
B)makes a transition to a lower energy level.
C)accelerates to a medium energy level.
D)none of the above

Question 13

The highest frequency of visible light is

A)red.
B)green.
C)blue.
D)violet.
E)all the same

Question 14

Neon atoms in a glass tube can be excited

A)once per atom.
B)repeatedly.
C)by infrared light.

Question 15

Colors seen in the flames of a burning log originate with the variety of

A)multi-layered incandescent surfaces.
B)electron transitions in various atoms.
C)temperatures.
D)absorbing gases between the log and the viewer.

Question 16

The energy of a photon depends on its

A)speed.
B)frequency.
C)amplitude.
D)all of the above
E)none of the above

Question 17

The air that you breathe doesn't emit visible light indicates that most of the electrons of its atoms are

A)in the ground state.
B)excited to metastable states.
C)relatively cool.
D)electrically neutral.
E)relatively far apart.

Question 18

An atom is excited when one or more of its electrons

A)vibrates.
B)is boosted into higher energy levels.
C)undergoes a frequency change.
D)becomes frantic.

Question 19

An excited atom is an atom

A)with excess vibration.
B)with one or more displaced electrons.
C)with more protons than electrons.
D)that is frantic.

Question 20

Physicists find that the energy states of atoms are

A)discrete.
B)circular.
C)elliptical.
D)chaotic.

Question 21

As a solid is gradually heated, it first glows

A)red.
B)yellow.
C)white.
D)blue.

Question 22

Spectral lines take the shape of vertical lines because

A)the light is vertically polarized.
B)they are images of a vertical slit.
C)the energy levels in the atom are parallel to one another.
D)all of the above
E)none of the above

Question 23

As the filament of a lamp is heated it changes

A)temperature.
B)color.
C)both of these
D)neither of these

Question 24

An object heated to twice the absolute temperature emits radiation

A)with twice the peak frequency.
B)in the ultraviolet part of the spectrum.
C)in the radio wave part of the spectrum.
D)with longer wavelengths.

Question 25

Comparing the light from a glowing tube of neon gas and the beam of a helium-neon laser, there is a greater number of spectral lines in light from the

A)neon gas tube.
B)laser beam.
C)both about the same

Question 26

If the energy levels in the neon atom were not discrete, neon signs would glow

A)red.
B)white.
C)blue.

Question 27

Sometimes a flashlight filament glows red instead of white, which indicates a lowness of

A)current in the filament.
B)filament temperature.
C)both of these
D)neither of these

Question 28

If wavelengths of emitted light become longer, the energy per photon of light

A)increases.
B)remains constant.
C)decreases.
D)none of the above

Question 29

When we say energy levels in an atom are discrete, we mean that their energy levels are well defined and

A)separate from one another.
B)separated by equal energy increments.
C)continuous.
D)private.

Question 30

If light in a spectroscope were passed through a star-shaped opening instead of a thin slit, spectral lines would appear as

A)lines of poorer resolution.
B)stars.
C)blobs of no definite shape.

Question 31

The spectral lines are more distinct when viewed in a mercury vapor lamp under

A)high pressure.
B)low pressure.
C)same for each

Question 32

If a certain object emits visible waves rather than infrared waves its temperature is

A)higher.
B)lower.
C)the same, temperature doesn't make any difference.

Question 33

The radiation curve for a red hot fire-place poker peaks in the

A)infrared region.
B)green region.
C)ultraviolet region.

Question 34

Discrete spectral lines are observed when excitation occurs in a

A)solid.
B)liquid.
C)gas.
D)superconductor.
E)all of the above

Question 35

Isolated bells ring clearly, while bells crammed in a box have a muffled ring. This is analogous to light emitted by

A)a laser.
B)a fluorescent lamp.
C)an incandescent lamp.
D)a phosphorescent source.
E)none of the above

Question 36

A violet-hot star emits radiation having about twice the peak frequency of radiation from a red-hot star. The surface temperature of the hotter star is about

A)half that of the cooler star.
B)twice that of the cooler star.
C)the same.

Question 37

The spectrum of a mercury vapor lamp under very high pressure appears as that from

A)an incandescent source.
B)a laser.
C)an ultraviolet source.
D)a gas other than mercury.
E)a monochromatic source.

Question 38

Which of the following continually emits electromagnetic radiation?

A)insects
B)radio antennas
C)red-hot coals
D)all of the above
E)none of the above

Question 39

The Doppler effect due to motion of excited atoms in a glowing gas tends to make the spectral lines slightly

A)thicker.
B)thinner.
C)more numerous.
D)none of the above

Question 40

If light in a spectroscope passed through round holes instead of slits, spectral lines would appear

A)as thicker lines.
B)round.
C)dimmer.

Question 41

Some minerals glow when illuminated with ultraviolet light because

A)ultraviolet photons boost atomic electrons in the mineral to higher energy states.
B)ultraviolet photons have high energy.
C)of selective reflection.
D)of selective transmission.
E)none of the above

Question 42

If the radiation curve for an incandescent lamp filament peaks in the green region, the object would appear

A)red.
B)yellow.
C)green.
D)blue.
E)white.

Question 43

Astronomers can tell whether a light source approaches or recedes from Earth by

A)its temperature.
B)its change in temperature.
C)its absorption spectra.
D)the Doppler effect.
E)all of the above

Question 44

The white light emitted by a fluorescent lamp is provided by the

A)mercury vapor in the lamp.
B)phosphors on the inner surface of the lamp.
C)high temperature of the glowing gas.
D)filtering effect of the glass tubing.

Question 45

Helium was first discovered in the

A)laboratory.
B)upper atmosphere.
C)Sun.
D)island of Helios, in Greece.
E)byproducts of nuclear fusion.

Question 46

The hottest star is the one that glows

A)red.
B)white.
C)blue.
D)need more information

Question 47

For absorption spectra to exist

A)the light source must be a gas.
B)partially absorbent material must exist between the light source and the spectroscope slit.
C)the spectroscope must be equipped with an absorption cell.
D)all of the above
E)none of the above

Question 48

The dark lines in the Sun's spectrum are due to light that is

A)absorbed by the Sun's atmosphere.
B)emitted by the Sun.
C)reflected by the Sun.
D)none of the above

Question 49

Fluorescent minerals on display in museums are illuminated with

A)infrared light.
B)ultraviolet light.
C)often either or both
D)none of these

Question 50

Astronomers can detect the spin rates of stars by

A)their temperature.
B)changes in temperature.
C)absorption spectra.
D)the Doppler effect.
E)all of the above

Question 51

If a material is heated until it is green hot, then

A)it would liquefy immediately.
B)it would be hotter than white hot.
C)its molecules would be vibrating at nearly identical rates.
D)it would be a strong absorber of red light.
E)energy conservation would be violated.

Question 52

The greater proportion of energy immediately converted to heat rather than light occurs in

A)a fluorescent lamp.
B)an incandescent lamp.
C)both of these
D)neither of these

Question 53

In the process of fluorescence, the input is high-frequency light and the output is

A)higher-frequency light.
B)equally high-frequency light.
C)lower-frequency light.
D)none of the above

Question 54

In the process of fluorescence, part of the input energy immediately

A)becomes internal energy with the rest as lower-frequency light.
B)cascades to excite other atoms in the material.
C)is emitted as higher-frequency light and the rest as lower-frequency light.
D)excites electrons to metastable states.
E)none of the above

Question 55

Light at the peak frequency of an incandescent lamp depends on the

A)amount of electrical energy transformed.
B)rate of atomic and molecular vibrations.
C)voltage applied to the lamp.
D)electrical resistance of the lamp.
E)transparency of glass.

Question 56

An atom that emits light of a certain frequency is

A)not likely to absorb that same frequency.
B)an absorber of light of the same frequency.
C)fluorescent.
D)none of the above

Question 57

A paint pigment that absorbs red light and gives off blue light

A)is fluorescent.
B)is phosphorescent.
C)is used in lasers.
D)is polarized.
E)doesn't exist.

Question 58

Iron absorption lines that occur in the solar spectrum indicate that iron exists in the solar

A)atmosphere.
B)surface.
C)interior.
D)none of the above

Question 59

The radiation curve for a blue hot star peaks in the

A)infrared region.
B)red region.
C)yellow region.
D)ultraviolet region.
E)none of the above

Question 60

Fraunhofer lines are apparent in

A)absorption spectra.
B)emission spectra.
C)Doppler shifts.
D)a variety of energy levels.
E)none of the above

Question 61

Which of these lamps employs semi-conductor technology?

A)incandescent lamp
B)fluorescent lamp
C)CFL
D)LED

Question 62

To keep chickens in a chicken coop warm, the kind of lamp to use is

A)fluorescent.
B)CFL.
C)incandescent.
D)LED.
E)all about the same

Question 63

Light from a laser is

A)monochromatic.
B)in phase.
C)coherent.
D)all of the above
E)none of the above

Question 64

Argon rather than air is the gas used in incandescent bulbs because

A)it produces a pleasing bluish glow.
B)oxygen in air oxidizes the lamp filament.
C)argon is relatively plentiful.
D)none of the above

Question 65

Which of these lamps has no mercury content?

A)fluorescent lamp
B)CFL
C)incandescent lamp
D)none of the above

Question 66

The efficiency of classroom-demonstration lasers is typically

A)about one percent.
B)about ten percent.
C)about twenty percent.
D)more than twenty percent.

Question 67

The absorption of an infrared photon that excites an atom to emit a green photon

A)occurs in plants.
B)occurs in the process of phosphorescence.
C)would violate the law of energy conservation.
D)all of the above
E)none of the above

Question 68

A watch dial that continues to glow after a week in the dark is almost certainly

A)fluorescent.
B)phosphorescent.
C)polarized.
D)radioactive.

Question 69

A laser cannot emit more energy than is put into it. But in instances where stored energy can be released in a very short time, the laser

A)puts out more energy than is put into it.
B)has a greater power output than power input.
C)both of these
D)neither of these

Question 70

White-light LEDs employ

A)phosphors.
B)white-emitting diodes.
C)extra-high electrical barriers.
D)none of the above

Question 71

The major difference between phosphorescent and fluorescent materials is

A)a time delay between excitation and de-excitation.
B)a difference in brightness.
C)the greenish color of phosphorescence.
D)none of the above

Question 72

The red laser beam from a helium-neon laser corresponds to a spectral line of

A)helium.
B)neon.
C)both of these
D)neither of these

Question 73

A helium-neon laser beam in a vacuum is

A)red.
B)orange.
C)white.
D)invisible.
E)none of the above

Question 74

Compared to the energy put into a laser, the energy of the laser beam is

A)usually much more.
B)much less.
C)the same.
D)none of the above

Question 75

Which light source is more energy-efficient?

A)a fluorescent lamp
B)an incandescent lamp
C)a CFL
D)an LED

Question 76

The lamp most similar to the common fluorescent lamp is the

A)LED.
B)CFL.
C)incandescent lamp.
D)none of the above

Question 77

Which light-emitting process is characterized by an afterglow?

A)incandescence.
B)fluorescence.
C)phosphorescence.
D)resonance.
E)none of the above

Question 78

Atoms can be excited by

A)thermal agitation.
B)electron impact.
C)photon impact.
D)all of the above
E)none of the above

Question 79

Some light switches that glow in the dark after the lights are turned off employ

A)fluorescence.
B)resonance.
C)incandescence.
D)all of the above
E)none of the above

Question 80

A paint pigment that absorbs blue light and gives off red light

A)is fluorescent.
B)is phosphorescent.
C)can be both of these
D)neither of these