Deck 27: Early Quantum Physics and the Photon

Question 1

Two lasers emit equal numbers of photons per second. If the first laser emits red light and the second emits blue light, the power radiated by the first is

A) equal to that emitted by the second.
B) greater than that emitted by the second.
C) less than that emitted by the second.
D) dependent on the time interval of the emission.

Answer 1

less than that emitted by the second.

Question 2

Silver has a work function of 4.73 eV. Photons of the threshold frequency would be described as which of the following?

A) infrared
B) red
C) yellow
D) blue
E) ultraviolet

Answer 2

ultraviolet

Question 3

A quantized item

A) has possible values that are limited to a discrete set.
B) applies only to very small objects.
C) applies only to very slow-moving objects.
D) can be any integer value.

Answer 3

has possible values that are limited to a discrete set.

Question 4

Using the quantum theory of EM waves, which scientist was successful in explaining the photoelectric effect (and later won a Nobel Prize for the work)?

A) Heinrich Hertz
B) Max Planck
C) Albert Einstein
D) James Clerk Maxwell
E) Niels Bohr

Question 5

The energy of a photon of wavelength 400 nm is

A) 3.11 × 10^-19 J
B) 3.50 × 10^-19 J
C) 3.87 × 10^-19 J
D) 4.25 × 10^-19 J
E) 4.97 × 10^-19 J

Question 6

The work function of a surface is 6.53 × 10^-19 J. What is this quantity in eV?

A) 2.46
B) 3.13
C) 3.93
D) 4.08
E) 4.70

Question 7

Sodium has a work function of 2.36 eV. Of the following choices, which is the one of the longest wavelength that could cause photoelectrons to be ejected from the sodium?

A) 300 nm
B) 400 nm
C) 500 nm
D) 600 nm
E) 700 nm

Question 8

Photons from a source each have energy 3.30 eV. Photons from a second source have twice the frequency as those from the first source. What is the energy of a photon from the second source?

A) 6.60 eV
B) 13.2 eV
C) 1.65 eV
D) 0.825 eV
E) 3.30 eV

Question 9

Which scientist proposed quantization of energy to overcome a major problem with understanding blackbody radiation?

A) Heinrich Hertz
B) Max Planck
C) Albert Einstein
D) James Clerk Maxwell
E) Niels Bohr

Question 10

A laser beam emits 2.5 × 10²⁰ photons per second with a wavelength of 663 nm. What is the power output of this laser?

A) 51 mW
B) 67 mW
C) 51 W
D) 75 W
E) 93 W

Question 11

What is the threshold frequency for a surface with work function 4.14 eV?

A) 1.00 × 10¹² Hz
B) 1.00 × 10¹³ Hz
C) 1.00 × 10¹⁴ Hz
D) 1.00 × 10¹⁵ Hz
E) 1.00 × 10¹⁶ Hz

Question 12

A 1.00 mW laser produces photons of wavelength 633 nm. How many photons per second does the laser emit?

A) 1.58 × 10³
B) 1.06 × 10¹⁰
C) 3.19 × 10¹⁵
D) 6.24 × 10¹⁵
E) 1.60 × 10¹⁹

Question 13

In a photoelectric effect experiment, the frequency of photons bombarding the surface is increased until photoelectrons just start to leave the surface. If this occurs at a frequency of 6.0 × 10¹⁴ Hz, what is the work function of the surface?

A) 1.0 eV
B) 1.5 eV
C) 2.0 eV
D) 2.5 eV
E) 3.0 eV

Question 14

Photons of red light cause a surface to emit photoelectrons with maximum kinetic energy K(red). If photons of blue light of the same intensity are now used in the experiment, which of the following statements is true about the photoelectrons emitted (if any are emitted)?

A) No photoelectrons are emitted.
B) maximum K(blue) < K(red)
C) maximum K(blue) = K(red)
D) maximum K(blue) > K(red)
E) None of these choices are true.

Question 15

Light of wavelength 400 nm bombards a surface that has a work function of 2.46 eV. What is the maximum kinetic energy of the photoelectrons from this surface?

A) No photoelectrons are emitted.
B) 2.46 eV
C) 3.30 eV
D) 0.640 eV
E) 0.840 eV

Question 16

A photon of frequency 6.40 × 10¹⁴ Hz has what energy?

A) 1.26 eV
B) 1.93 eV
C) 2.11 eV
D) 2.65 eV
E) 3.17 eV

Question 17

A problem with the classical theory for radiation from a blackbody was that the theory predicted too much radiation in what range of wavelengths?

A) ultraviolet
B) visible
C) infrared
D) microwave
E) radio

Question 18

A 2.00 eV photon has what frequency?

A) 6.40 × 10¹⁴ Hz
B) 1.86 × 10¹⁴ Hz
C) 3.15 × 10¹⁴ Hz
D) 7.21 × 10¹⁴ Hz
E) 4.84 × 10¹⁴ Hz

Question 19

In Compton scattering, a photon of wavelength λ and frequency f is scattered from an electron, initially at rest. In this process,

A) the electron gains energy from the photon so that the scattered photon's wave length is less than λ.
B) the electron gives energy to the scattered photon so the photon's frequency is greater than f.
C) momentum is not conserved, but energy is conserved.
D) the photon loses energy so that the scattered photon has a frequency less than f.

Question 20

An x-ray photon of energy 3.20 × 10^-15 J has what wavelength?

A) 200 nm
B) 62.1 pm
C) 32.7 nm
D) 5.73 pm
E) 1.07 nm

Question 21

Electrons are accelerated through a potential difference of 90.0 kV and directed at a tungsten target to produce x-rays. What is the cutoff frequency of the x-ray spectrum produced?

A) 2.18 × 10¹⁹ Hz
B) 2.10 × 10¹⁹ Hz
C) 1.17 × 10²¹ Hz
D) 9.25 × 10²¹ Hz
E) 6.20 × 10¹⁵ Hz

Question 22

In a Compton scattering experiment, the scattered photon has a wavelength of 6.55 pm. If the scattering angle is 50°, what was the wavelength of the incident photon?

A) 5.68 pm
B) 7.42 pm
C) 3.28 pm
D) 0.868 pm
E) 2.43 pm

Question 23

Electrons are accelerated through a potential difference of 90.0 kV and directed at a tungsten target to produce x-rays. What is the shortest wavelength of the x-rays produced?

A) 669 pm
B) 508 pm
C) 72.6 pm
D) 13.8 pm
E) 14.3 pm

Question 24

Electrons are accelerated through a potential difference V and then strike a dense target. In the x-rays that are produced,

A) the maximum wavelength depends on V.
B) the wavelengths of the characteristic peaks depend on V.
C) the minimum wavelength depends on V.
D) the speed of the x-rays depends on V.

Question 25

An x-ray photon with wavelength 15.0 pm is scattered through 84.0° by an electron. What is the resulting kinetic energy of the electron?

A) 568 keV
B) 59.5 keV
C) 30.1 keV
D) 15.0 keV
E) 10.5 keV

Question 26

The Compton shift equation for the change in wavelength of a scattered photon is derived from the law(s) of

A) conservation of momentum.
B) conservation of energy.
C) conservation of charge.
D) conservation of momentum and charge.
E) conservation of energy and momentum.

Question 27

In a Compton scattering experiment, the scattered photon has a wavelength of 6.55 pm. If the scattering angle is 50°, what is the energy of the incident photon?

A) 1.43 MeV
B) 218 keV
C) 380 keV
D) 117 keV
E) 66.3 keV

Question 28

The mathematician Johann Jakob Balmer found that the formula 1/λ = R (1/n_f² − 1/n_i²) works for the hydrogen emission lines in the visible range, with what value of n_f?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 29

The number of electrons per second ejected from a metal in the photoelectric effect

A) is proportional to the threshold frequency of the metal.
B) is proportional to the intensity of the incident light.
C) is proportional to the threshold wavelength of the incident light.
D) is proportional to the frequency of the incident light.

Question 30

Photons of energy 4.20 eV bombard a surface, which emits photoelectrons with kinetic energies from 0 to 1.80 eV. What is the threshold frequency for this surface?

A) 1.35 × 10¹⁴ Hz
B) 5.80 × 10¹⁴ Hz
C) 1.35 × 10¹⁵ Hz
D) 7.74 × 10¹⁴ Hz
E) 7.74 × 10¹⁵ Hz

Question 31

The maximum shift in wavelength in Compton scattering is what multiple of the Compton wavelength (h/m_ec)?

A) 0.5
B) 1
C) 2
D) 4
E) unlimited

Question 32

Monochromatic light shines on a surface that has a work function of 1.80 eV. The maximum kinetic energy of the emitted photoelectrons is 0.620 eV. What is the wavelength of the monochromatic light?

A) 200 nm
B) 290 nm
C) 689 nm
D) 602 nm
E) 512 nm

Question 33

A 100 keV photon undergoes Compton scattering. What is the greatest amount of kinetic energy that can be given to the electron in this process?

A) 100 keV
B) 71.8 keV
C) 83.6 keV
D) 28.1 keV
E) 16.4 keV

Question 34

An x-ray tube produces photons with wavelengths down to a minimum of 0.0827 nm. What is the accelerating potential for this tube?

A) 123 kV
B) 9.22 kV
C) 8.00 kV
D) 10.0 kV
E) 15.0 kV

Question 35

In a photoelectric effect experiment, light of a single wavelength is incident on the metal surface. As the intensity of the incident light is increased

A) the stopping potential decreases.
B) the stopping potential increases.
C) the work function decreases.
D) the work function increases.
E) None of these choices are true.

Question 36

How many emission lines are possible for atomic hydrogen gas with atoms excited to the n = 4 state?

A) 1
B) 2
C) 4
D) 5
E) 6

Question 37

What kind of spectra did the physicist Anders Jonas Ångström discover in his study of low-pressure gas discharge tubes?

A) continuous
B) discrete
C) blackbody
D) band
E) dark-line

Question 38

An x-ray photon with wavelength 15.0 pm is scattered at 84.0° by an electron. What is the wavelength of the scattered photon?

A) 31.0 pm
B) 14.9 pm
C) 1.57 pm
D) 17.2 pm
E) 12.8 pm

Question 39

X-rays are produced by an x-ray tube with an applied potential difference of V. The spectrum of wavelengths is found to contain

A) a single wavelength.
B) all wavelengths below a maximum.
C) all wavelengths above a minimum.
D) only discrete wavelengths.

Question 40

An electron passing close to a target nucleus slows and radiates away some of its energy. What is the process called?

A) blackbody radiation
B) photoelectric effect
C) stimulated emission
D) bremsstrahlung
E) Compton scattering

Question 41

What is the radius of the ground state of He⁺?

A) 0.0529 nm
B) 0.193 nm
C) 0.0265 nm
D) 0.106 nm
E) 0.212 nm

Question 42

Which scientist proposed the nuclear model of the atom as a result of experiments involving alpha particle scattering?

A) Albert Einstein
B) Niels Bohr
C) Ernest Rutherford
D) Max Planck
E) Richard Feynman

Question 43

According to the Bohr model, the kinetic energy of an electron in a stationary state in hydrogen is what factor times its potential energy?

A) 1
B) −1
C) 1/2
D) −1/2
E) 2

Question 44

The minimum energy that a photon must have to create an electron-positron pair is

A) 0.511 MeV.
B) 1.022 MeV.
C) 2.044 MeV.
D) 0.256 MeV.
E) any amount more than zero.

Question 45

If a hydrogen atom in the ground state absorbs a 20.0 eV photon, what kinetic energy of the electron results?

A) this cannot happen
B) 20.0 eV
C) 13.6 eV
D) 6.4 eV
E) 33.6 eV

Question 46

If pair production of a muon-antimuon pair can occur for a photon of wavelength 5.85 fm or less, what is the mass of a muon? (muons and antimuons have the same mass.)

A) 212 MeV/c²
B) 106 MeV/c²
C) 424 MeV/c²
D) 0.511 MeV/c²
E) 1.02 MeV/c²

Question 47

According to the Bohr model, what is the kinetic energy of an electron in the ground state of hydrogen?

A) 0
B) 13.6 eV
C) 6.80 eV
D) 27.2 eV
E) 1.88 eV

Question 48

In the Bohr model of the hydrogen atom, the stationary states are circular orbits in which what property of the electron is quantized in integral multiples of h/2π?

A) kinetic energy
B) potential energy
C) total energy
D) linear momentum
E) angular momentum

Question 49

What is the highest energy of a photon in the Balmer series?

A) 1.89 eV
B) 3.40 eV
C) 1.51 eV
D) 0.94 eV
E) 0.66 eV

Question 50

For the ion He⁺, what is the energy of the ground state?

A) -13.6 eV
B) −27.2 eV
C) −54.4 eV
D) −6.80 eV
E) −3.40 eV

Question 51

What is the energy of a photon emitted in a transition from the n = 3 state to the n = 2 state in He⁺?

A) 15.1 eV
B) 7.56 eV
C) 3.78 eV
D) 2.12 eV
E) 1.89 eV

Question 52

According to the Bohr model, what is the potential energy of an electron in the ground state of the hydrogen atom?

A) 0
B) −13.6 eV
C) −27.2 eV
D) 13.6 eV
E) 27.2 eV

Question 53

What is the smallest energy photon that a hydrogen atom in the ground state can absorb?

A) any energy
B) 13.6 eV
C) 10.2 eV
D) 3.40 eV
E) 1.90 eV

Question 54

What is the ratio of the Bohr orbital radius for hydrogen in the n = 3 state to that in the n = 1 state?

A) 1/3
B) 3
C) 6
D) 9
E) 18

Question 55

What is the ionization energy of the hydrogen atom in the n = 2 state?

A) 13.6 eV
B) −13.6 eV
C) 3.40 eV
D) −3.40 eV
E) −1.51 eV

Question 56

What is the wavelength of the photon emitted when a hydrogen atom makes a transition from the n = 4 state to the n = 1 state?

A) 323 nm
B) 156 nm
C) 121 nm
D) 103 nm
E) 97.3 nm

Question 57

A photon that is emitted during a transition in hydrogen from the n = 27 state to the n = 2 state is in which of the following series?

A) Lyman
B) Balmer
C) Paschen
D) Brackett
E) All of these choices are correct.

Question 58

Electrons are used to produce x-rays by allowing a beam of electrons to strike a heavy metal surface. When the intensity of the electron beam is increased, this produces

A) x-rays with longer wavelengths.
B) x-rays with higher energy.
C) more x-rays per unit time.
D) faster x-rays.

Question 59

Which of the following statements is true?

A) All the photons of the Lyman series are in the ultraviolet.
B) Some of the photons of the Lyman series are in the visible.
C) Some of the photons of the Lyman series are in the infrared.
D) All the photons of the Balmer series are in the visible.
E) All these statements are false.

Question 60

PET, the diagnostic method, stands for

A) patterned electron technique.
B) positron emission tomography.
C) proton-electron transmission.
D) penetrating emission technique.
E) None of these choices are correct.

Question 61

Dark lines in the spectra observed from stellar atmospheres indicate that

A) atoms that would produce the missing frequency bands aren't present in the atmosphere.
B) atoms are present in the atmosphere that are absorbing photons of those frequencies.
C) atoms are present in the atmosphere that are emitting photons of those frequencies.
D) atoms that would produce the missing frequency bands are forbidden from doing so because of quantum effects.

Question 62

What is the maximum wavelength photon that can produce a pair of tau particles (mass 1.777 GeV/c²) by pair production?

A) 8.72 × 10⁻⁸ nm
B) 3.49 × 10⁻⁷ nm
C) 6.98 × 10⁻⁷ nm
D) 1.74 × 10⁻⁷ nm

Question 63

An electron and positron, each having kinetic energy 10 MeV, annihilate and produce two photons. What is the wavelength of each photon?

A) 0.124 pm
B) 0.118 pm
C) 0.248 pm
D) 0.062 pm
E) need more information

Question 64

Electrons are used to produce x-rays by allowing a beam of electrons to strike a heavy metal surface. What is true about the wavelengths of the characteristic x-rays that are produced in such a situation?

A) There is a continuous range of wavelengths produced, up to a maximum that depends on the energy of the electron beam used.
B) There is a single wavelength of x-ray produced that depends on the energy of the electron beam used.
C) There are a few specific wavelengths that are produced for a given metal and their wavelengths are independent of the energy of the electron beam used.
D) There is a continuous range of wavelengths produced, down to a minimum that depends on the energy of the electron beam used.

Question 65

A Compton scattering experiment is performed in which the scattered photons have a minimum energy of 17.2 keV. What was the incident energy of the photons used in this experiment?

A) 16.6 keV
B) 18.4 keV
C) 16.1 keV
D) 17.2 keV

Question 66

Ultraviolet light is shone on a piece of metal, and electrons are observed to be ejected from the metal. The UV lamp is now replaced by a lamp of the same intensity, but which produces photons having a shorter wavelength. Which of the below differences is observed?

A) More electrons per unit time are produced.
B) Nothing changes at all.
C) Electrons with a higher maximum energy are observed.
D) Electrons with lower maximum energy are observed.

Question 67

Which of the following did the planetary model of the atom fail to explain?

A) the relationship between orbital radius and energy
B) why some alpha particles in Rutherford's scattering experiment deflected at high angles when incident on atomic foils
C) why most alpha particles in Rutherford's scattering experiment passed with little deflection through atomic foils
D) why electrons in atoms don't radiate all their energy away rapidly

Question 68

Electrons are used to produce x-rays by allowing a beam of electrons to strike a heavy metal surface. What is true about the wavelengths of the bremsstrahlung x-rays that are produced in such a situation?

A) There are a few specific wavelengths that are produced for a given metal and their wavelengths are independent of the energy of the electron beam used.
B) There is a single wavelength of x-ray produced that depends on the energy of the electron beam used.
C) There is a continuous range of wavelengths produced, down to a minimum that depends on the energy of the electron beam used.
D) There is a continuous range of wavelengths produced, up to a maximum that depends on the energy of the electron beam used.

Question 69

A photocell is a device that operates using the photoelectric effect. What metal would enable a photocell to be operated using visible light?

A) manganese (φ = 4.1 eV)
B) lanthanum (φ = 3.5 eV)
C) cesium (φ = 1.95 eV)
D) beryllium (φ = 4.98 eV)

Question 70

Ultraviolet light is shone on a piece of metal, and electrons are observed to be ejected from the metal. The UV lamp is now replaced by a lamp of the same intensity, but which produces photons having a shorter wavelength. What difference is observed in the number of electrons produced per unit time?

A) The same number are produced.
B) Fewer are produced.
C) More are produced.
D) Without knowing more about the wavelengths used, one cannot answer.

Question 71

X-rays of wavelength 0.240 nm are scattered from a free electron at rest and the resulting scattered photons have wavelength 0.244 nm. Through what angle did these photons scatter relative to the initial direction?

A) 130°
B) 80°
C) such scattering is impossible
D) 34°

Question 72

Ultraviolet light is shone on a piece of metal, and electrons are observed to be ejected from the metal. The UV lamp is now replaced by a lamp of the same intensity, but which produces photons having a longer wavelength. If the new photon energy is still sufficient to overcome the work function of the metal and eject electrons, what difference is observed in the number of electrons produced per unit time?

A) The same number are produced.
B) More are produced.
C) Fewer are produced.
D) Without knowing more about the wavelengths used, one cannot answer.

Question 73

Electrons are used to produce x-rays by allowing a beam of electrons to strike a heavy metal surface. When the speed of the electrons in the beam is increased, this produces

A) x-rays with higher energies
B) x-rays with longer wavelengths
C) faster x-rays
D) more x-rays per unit time

Question 74

Light with the wavelength of peak intensity from a star can just barely produce photoelectrons from manganese (φ = 4.1 eV). What is the temperature of the star?

A) 960 K
B) 23000 K
C) 9600 K
D) 96000 K
E) 2300 K