Deck 5: Light

Question 1

What wavelengths of light can the human eye see?

A) 3.8-7.5 $\mu$ m
B) 3.8-7.5 nm
C) 380-750 cm
D) 380-750 nm
E) 3.8-7.5 m

Answer 1

380-750 nm

Question 2

The fact that the speed of light is constant as it travels through a vacuum means that

A) photons with longer wavelengths have lower frequencies.
B) radio wave photons have shorter wavelengths than gamma-ray photons.
C) X-rays can be transmitted through the atmosphere around the world.
D) ultraviolet photons have less energy than visible photons.
E) all photons have the same wavelength.

Answer 2

photons with longer wavelengths have lower frequencies.

Question 3

Which of the following lists different types of electromagnetic radiation in order from the shortest wavelength to the longest wavelength?

A) radio waves, infrared, visible, ultraviolet, X-rays
B) gamma rays, ultraviolet, visible, infrared, radio waves
C) gamma rays, X-rays, infrared, visible, ultraviolet
D) X-rays, infrared, visible, ultraviolet, radio waves
E) radio waves, ultraviolet, visible, infrared, gamma rays

Answer 3

gamma rays, ultraviolet, visible, infrared, radio waves

Question 4

Light has aspects of

A) only a wave.
B) only a particle.
C) both a particle and a wave.
D) neither a particle nor a wave.
E) none of these are correct.

Question 5

The speed of light in a vacuum is

A) 300,000 m/s.
B) 300,000 mph.
C) 300,000 km/s.
D) 300,000,000 mph.
E) infinite.

Question 6

The term quantum refers to

A) anything that is very small.
B) a way of grouping small things together for mathematical convenience.
C) a single, smallest possible unit of some quantity.
D) uncertain, theoretical concepts.
E) something that behaves randomly.

Question 7

Saying that something is quantized means that it

A) is a wave.
B) can only be observed using a telescope.
C) travels at the speed of light.
D) can only have discrete quantities.
E) is smaller than an atom.

Question 8

The amplitude of a wave is

A) the total distance a wave travels
B) a measure of the wave's velocity.
C) the number of peaks that pass per second.
D) the maximum height of the wave above zero.
E) the distance between one peak value and the next peak.

Question 9

What is the difference between visible light and X-rays?

A) Speed; X-rays go faster than visible light.
B) Speed; X-rays go slower than visible light.
C) Wavelength; X-rays have a shorter wavelength than visible light.
D) Wavelength; X-rays have a longer wavelength than visible light.
E) X-rays are made up of particles, whereas visible light is made up of waves.

Question 10

Which of the following photons carries the smallest amount of energy?

A) a blue photon of the visible spectrum, whose wavelength is 450 nm
B) an infrared photon, whose wavelength is 10^-5 m
C) a red photon in the visible spectrum, whose wavelength is 700 nm
D) a microwave photon, whose wavelength is 10^-2 m
E) an ultraviolet photon, whose wavelength is 300 nm

Question 11

How do the wavelength and frequency of red light compare to the wavelength and frequency of blue light?

A) Red light has a longer wavelength and higher frequency than blue light.
B) Red light has a longer wavelength and lower frequency than blue light.
C) Red light has a shorter wavelength and higher frequency than blue light.
D) Red light has a shorter wavelength and lower frequency than blue light.
E) Red light and blue light will have the same frequencies and wavelengths.

Question 12

The color of visible light is determined by its

A) speed.
B) wavelength.
C) mass.
D) distance from you.
E) size.

Question 13

Which formula denotes how the speed of light is related to its wavelength and frequency?

A) c = $\lambda$ f
B) c = $\lambda$ /f
C) c =f / $\lambda$
D) c = 1/ $\lambda$ f
E) There is no relationship between wavelength and frequency.

Question 14

The wavelength of a wave is

A) the total distance a wave travels
B) a measure of the wave's velocity.
C) the number of peaks that pass per second.
D) the maximum height of the wave above zero.
E) the distance between one peak value and the next peak.

Question 15

If the wavelength of a beam of light were to double, how would that affect its frequency?

A) The frequency would be four times higher.
B) The frequency would be two times higher.
C) The frequency would be two times lower.
D) The frequency would be four times lower.
E) There is no relationship between wavelength and frequency.

Question 16

When talking about a wave, what does the term medium refer to?

A) the size of an object
B) the substance through which the wave travels
C) the brightness level
D) the vacuum
E) the wavelength range of that wave

Question 17

Radio waves have wavelengths of

A) less than 0.1 nanometer.
B) between 0.1 nanometer and 40 nanometers.
C) between 40 nanometers and 380 nanometers.
D) between 1,000 nanometers and 500 microns.
E) more than a few centimeters.

Question 18

How does the speed of light traveling through a medium (such as air or glass) compare to the speed of light in a vacuum?

A) It is the same as the speed of light in a vacuum.
B) It is always less than the speed of light in a vacuum.
C) It is always greater than the speed of light in a vacuum.
D) Sometimes it is greater than the speed of light in a vacuum and sometimes it is less, depending on the medium.
E) Light can't travel through a medium; it only can go through a vacuum.

Question 19

A nanometer is ________ of a meter.

A) 1/100
B) 1/1,000
C) 1/1,000,000
D) 1/1,000,000,000
E) 1/1,000,000,000,000

Question 20

________ measured the speed of light using the timing of Jupiter's moon.

A) Galileo
B) Newton
C) Kepler
D) Rømer
E) Einstein

Question 21

A certain light wave has a frequency of 3 *10⁸ Hz.What is its wavelength?

A) 500 nanometers
B) 10 nanometers
C) 100 microns
D) 1.0 meter
E) 3 * 10⁸ meters

Question 22

In the energy level diagram shown in the figure below, the electron is excited to the E₂ energy level.If the atom absorbs a photon with the exact wavelength to move the electron to another energy level, which energy level would correspond to the incoming photon with the largest wavelength?

A) E₁
B) E₂
C) E₃
D) E₄
E) E₅

Question 23

If the frequency of a beam of light were to increase, its period would ________ and its wavelength would ________.

A) decrease; increase
B) increase; decrease
C) increase; increase
D) decrease; decrease
E) stay the same; stay the same

Question 24

Which of these objects would emit an absorption spectrum?

A) an incandescent lightbulb
B) a fluorescent lightbulb
C) an isolated hot gas cloud
D) a hot, solid object
E) a thin, cool gas cloud that lies in front of a hotter blackbody

Question 25

The n = 5 electronic energy level in a hydrogen atom is 1.5 *10^-19 J higher than the n = 3 level.If an electron moves from the n = 5 level to the n = 3 level, then a photon of wavelength

A) 1.3 nm, which is in the ultraviolet region, is emitted.
B) 1.3 nm, which is in the ultraviolet region, is absorbed.
C) 1,300 nm, which is in the infrared region, is absorbed.
D) 1,300 nm, which is in the infrared region, is emitted.
E) No light will be absorbed or emitted.

Question 26

When an electron moves from a higher energy level in an atom to a lower energy level,

A) the atom is ionized.
B) a continuous spectrum is emitted.
C) a photon is emitted.
D) a photon is absorbed.
E) the electron loses mass.

Question 27

The figure below illustrates a stellar spectrum.The dip in the data near 650 nm corresponds most closely with which of the following?

A) sodium emission
B) sodium absorption
C) hydrogen emission
D) hydrogen absorption
E) iron absorption

Question 28

In the energy level diagram shown in the figure below, the electron is excited to the E₄ energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest frequency?

A) E₁
B) E₂
C) E₃
D) E₄
E) E₅

Question 29

The frequency of a wave is

A) the total distance a wave travels
B) a measure of the wave's velocity.
C) the number of peaks that pass per second.
D) the maximum height of the wave above zero.
E) the distance between one peak value and the next peak.

Question 30

Light with a wavelength of 600 nm has a frequency of

A) 2 *10⁵ Hz
B) 5 * 10⁷ Hz
C) 2 *10¹⁰ Hz
D) 5 * 10¹² Hz
E) 5 * 10¹⁴ Hz

Question 31

In the energy level diagram shown in the figure below, the electron is excited to the E₄ energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest wavelength?

A) E₁
B) E₂
C) E₃
D) E₄
E) E₅

Question 32

In the quantum mechanical view of the atom, electrons are often depicted as

A) a cloud that is centered on the nucleus.
B) a particle orbiting the nucleus.
C) free to orbit at any distance from the nucleus.
D) a particle inside the nucleus.
E) nothing, electrons are not part of an atom.

Question 33

As wavelength increases, the energy of a photon ________ and its frequency ________.

A) increases; decreases
B) increases; increases
C) decreases; decreases
D) decreases; increases
E) decreases; does not change.

Question 34

The Doppler shift can be used to determine the ________ of an object.

A) energy
B) temperature
C) radial velocity
D) color
E) three-dimensional velocity

Question 35

If you observe the spectrum of an isolated hot cloud of gas, you will see

A) an absorption spectrum.
B) a continuous spectrum.
C) an emission spectrum.
D) a rainbow spectrum.
E) a dark spectrum.

Question 36

In the energy level diagram shown in the figure below, the electron is excited to the E₄ energy level.If the electron transitions to an energy level giving off a photon, which level would produce a photon with the largest energy?

A) E₁
B) E₂
C) E₃
D) E₄
E) E₅

Question 37

A red photon has a wavelength of 650 nm.An ultraviolet photon has a wavelength of 250 nm.The energy of an ultraviolet photon is ________ the energy of a red photon.

A) 2.6 times larger than
B) 6.8 times larger than
C) 2.6 times smaller than
D) 6.8 times smaller than
E) the same as

Question 38

In the energy level diagram shown in the figure below, the electron is excited to the E₂ energy level.If the atom absorbs a photon with the exact frequency to move the electron to another energy level, which energy level would correspond to the incoming photon with the largest frequency?

A) E₁
B) E₂
C) E₃
D) E₄
E) E₅

Question 39

If you observe the spectrum of a star, you will see

A) an absorption spectrum.
B) a continuous spectrum.
C) an emission spectrum.
D) a rainbow spectrum.
E) a dark spectrum.

Question 40

Why is a neutral iron atom a different element from a neutral carbon atom?

A) A carbon atom has fewer neutrons in its nucleus than an iron atom.
B) An iron atom has more protons in its nucleus than a carbon atom.
C) An iron atom has more electrons than a carbon atom.
D) A carbon atom is bigger than an iron atom.
E) None of these is correct.

Question 41

Compare two blackbody objects, one at 200 K and one at 400 K.How much larger is the flux from the 400 K object compared to the flux from the 200 K object?

A) 2 times larger
B) 4 times larger
C) 8 times larger
D) 16 times larger
E) They have the same flux.

Question 42

You observe the spectrum of two stars.Star A has an emission line from a known element at 600 nm.Star B has emission lines from the same atom, but the emission line is occurring at 650 nm.One possible explanation for this observation is that star A is

A) cooler than star B.
B) farther away from us than star B.
C) moving toward us faster than star B.
D) made of different elements than star B.
E) larger than star B.

Question 43

If the quantity of something entering a system is equal to the quantity of that same thing leaving that system, we say the system is

A) quantized.
B) in equilibrium.
C) acting like a wave.
D) Doppler shifted.
E) dynamically unbalanced.

Question 44

You record the spectrum of a star and find that a calcium absorption line has an observed wavelength of 394.0 nm.This calcium absorption line has a rest wavelength of 393.3 nm.What is the approximate radial velocity of this star?

A) 5,000 km/s
B) 500 km/s
C) 50 km/s
D) 5 km/s
E) 0.5 km/s

Question 45

If you find that the hydrogen alpha line in a star's spectrum occurs at a wavelength of 656.45 nm, what is the star's approximate radial velocity? Note that the rest wavelength of this line is 656.30 nm.

A) 150 km/s away from you
B) 150 km/s toward you
C) 350 km/s toward you
D) 70 km/s away from you
E) 70 km/s toward you

Question 46

You observe a red star and a blue star and are able to determine that they are the same size.Which star has a higher surface temperature, and which star is more luminous?

A) The red star has a higher surface temperature and is more luminous.
B) The red star has a higher surface temperature, and the blue star is more luminous.
C) The blue star has a higher surface temperature and is more luminous.
D) The blue star has a higher surface temperature, and the red star is more luminous.
E) They have the same luminosities and temperatures.

Question 47

The Kelvin temperature scale is used in astronomy because

A) at 0 K an object has zero thermal energy.
B) water freezes at 0 K.
C) water boils at 100 K.
D) hydrogen freezes at 0 K.
E) the highest temperature possible is 1000 K.

Question 48

At what temperature does water freeze?

A) 0 K
B) 32 K
C) 100 K
D) 273 K
E) 373 K

Question 49

Why do some stars in the sky appear blue, whereas other stars appear red?

A) The red stars have higher surface temperatures than the blue stars.
B) The blue stars have higher surface temperatures than the red stars.
C) The blue stars are closer to us than the red stars.
D) The red stars are closer to us than the blue stars.
E) The blue stars are moving toward us, while red stars are moving away from us.

Question 50

You are driving on the freeway when a police officer records a shift of -7 nm when he or she measures your speed with a radar gun that operates at a wavelength of 0.1 m.How fast were you going?

A) 43 mph
B) 83 mph
C) 21 mph
D) 65 mph
E) 47 mph

Question 51

In the figure below, which blackbody spectrum corresponds to the object that would appear white to the human eye?

A) A
B) B
C) C
D) D
E) E

Question 52

As an object's temperature increases, the atoms inside that object

A) gain electrons.
B) increase in mass.
C) move at higher velocities.
D) emit less red light.
E) get larger.

Question 53

What does it mean to say that an object is in thermal equilibrium?

A) It isn't absorbing any energy.
B) It isn't radiating any energy.
C) It is radiating more energy than it is absorbing.
D) It is absorbing more energy than it is radiating.
E) It is absorbing the same amount of energy that it is radiating.

Question 54

Which of these stars would have the biggest redshift?

A) a star moving at low speed toward you
B) a star moving at high speed toward you
C) a star moving at low speed away from you
D) a star moving at high speed away from you
E) a star that is not moving away from you or toward you

Question 55

In the figure below, which blackbody spectrum corresponds to the object that would appear the reddest to the human eye?

A) A
B) B
C) C
D) D
E) E

Question 56

Consider an incandescent lightbulb.If you wanted to turn a 10-W lightbulb into a 100-W lightbulb, how would you change the temperature of the filament inside the bulb?

A) Raise its temperature by a factor of 3.2.
B) Raise its temperature by a factor of 1.8.
C) Raise its temperature by a factor of 10.
D) Lower its temperature by a factor of 2.6.
E) Lower its temperature by a factor of 5.4.

Question 57

As a blackbody's temperature increases, it also becomes ________ and ________.

A) more luminous; redder
B) more luminous; bluer
C) less luminous; redder
D) less luminous; bluer
E) more luminous; stays the same color

Question 58

A spaceship is traveling at a speed of 15,000 km/s from planet "B" toward planet "A." The spaceship sends out a signal with a wavelength of 4 m.If astronomers living on planets A and B measure the radio waves coming from the spaceship, what wavelengths will they measure?

A) Planet A measures 6 m, and planet B measures 2 m.
B) Planet A measures 2 m, and planet B measures 6 m.
C) Planet A measures 4.2 m, and planet B measures 3.8 m.
D) Planet A measures 3.8 m, and planet B measures 4.2 m.
E) Both Planet A and planet B measure 4 m.

Question 59

In the figure below, which blackbody spectrum corresponds to the object with the highest temperature?

A) A
B) B
C) C
D) D
E) E

Question 60

A spaceship is traveling toward Earth while giving off a constant radio signal with a wavelength of 1 meter (m).What will the signal look like to people on Earth?

A) a signal with a wavelength less than 1 m
B) a signal with a wavelength more than 1 m
C) a signal moving faster than the speed of light
D) a signal moving slower than the speed of light
E) a signal with a wavelength of 1 m, moving the normal speed of light

Question 61

The average red giant is about 1,000 times more luminous than the average main-sequence star.If both kinds of stars have about the same brightness in our night sky, how much farther away are the red giants compared to the main-sequence stars?

A) 32 times farther
B) 1,000 times farther
C) 65 times farther
D) 5.6 times farther
E) The red giants and main-sequence stars are approximately the same distance away.

Question 62

Describe, in your own words, why electrons cannot orbit the nucleus like the planets orbit the Sun.

Question 63

Why do we see black lines in an absorption spectrum if the absorbed photons are (almost) instantaneously reemitted by the atoms in the cloud?

Question 64

Which of these planets would be expected to have the highest average temperature?

A) a light-colored planet close to its star
B) a dark-colored planet close to its star
C) a light-colored planet far from its star
D) a dark-colored planet far from its star
E) There is not enough information to know which would be the hottest.

Question 65

If a star has a peak wavelength of 290 nm, what is its surface temperature?

A) 1000 K
B) 2000 K
C) 5000 K
D) 10,000 K
E) 100,000 K

Question 66

A spaceship approaches Earth at 0.9 times the speed of light and shines a powerful searchlight onto Earth.How fast will the photons from this searchlight be moving when they hit Earth?

Question 67

What different processes produce the patterns of light that can be viewed as: continuous spectra; emission spectra; and absorption spectra?

Question 68

The difference in energy between the n = 2 and n =1 electronic energy levels in the hydrogen atom is 1.6 *10^-18 J.If an electron moves from the n = 1 level to the n=2 level, will a photon be emitted or absorbed? What will its energy be, and what type of electromagnetic radiation is it? Use the electromagnetic spectrum shown in the figure below to answer this question.

Question 69

Star C and star D have the same luminosity.Star C is twice as far away from Earth as star D.How do the brightness levels of stars C and D compare?

A) Star C appears four times as bright as star D.
B) Star C appears twice as bright as star D.
C) Star D appears twice as bright as star C.
D) Star D appears four times as bright as star C.
E) Stars C and D appear equally bright.

Question 70

If the Sun's luminosity were twice its actual value, Earth's temperature would

A) more than double.
B) double.
C) increase, but be less than double.
D) not be different.
E) decrease a small amount.

Question 71

Compare the differences between a photon of red light and a photon of blue light.

Question 72

At what peak wavelength does your body radiate the most given that your temperature is approximately that of Earth, which is 300 K?

A) 10^-5 m
B) 10^-3 m
C) 10^-2 m
D) 10 m
E) 1,000 m

Question 73

The first five energy levels of hydrogen are E₁ = 0 eV, E₂ = 10.2 eV, E₃ =12.1 eV, E₄ =12.7 eV, and E₅ = 13.1 eV.If the electron is in the n = 4 level, what energies can a single emitted photon have?

Question 74

If a lightbulb is moved twice as far away, its luminosity will be

A) doubled.
B) quadrupled.
C) halved.
D) 1/4 the original.
E) the same.

Question 75

How is the energy of a photon related to its frequency, wavelength, and speed?

Question 76

How are atoms excited, and why do they become de-excited?

Question 77

If Jupiter has a temperature of 165 K, at what wavelength does its spectrum peak? Use the electromagnetic spectrum in the figure below to answer this question.

A) 18 nm-orange visible wavelengths
B) 1,800 mm-microwave wavelengths
C) 1,800 nm-infrared wavelengths
D) 18,000 nm-ultraviolet wavelengths
E) 18,000 nm-infrared wavelengths

Question 78

If the typical temperature of a red giant is 3000 K, at what wavelength is its radiation the brightest? Use the electromagnetic spectrum in the figure below to help you answer this question.

A) 1 $\mu$ m-infrared wavelengths
B) 1 $\mu$ m-red visible wavelengths
C) 20 $\mu$ m-infrared wavelengths
D) 20 $\mu$ m-red visible wavelengths
E) 700 $\mu$ m-red visible wavelengths

Question 79

Star A and star B appear equally bright in the sky.Star A is twice as far away from Earth as star B.How do the luminosities of stars A and B compare?

A) Star A is twice as luminous as star B.
B) Star B is twice as luminous as star A.
C) Star A is four times as luminous as star B.
D) Star B is four times as luminous as star A.
E) Stars A and B have the same luminosity.

Question 80

What is an electromagnetic wave?