Deck 38: Quantization

Question 1

When a certain metal is illuminated by light, photoelectrons are observed provided that the wavelength of the light is less than 669 nm. Which one of the following values is closest to the work function of this metal? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 1.9 eV
B) 2.0 eV
C) 2.2 eV
D) 2.3 eV

Answer 1

1.9 eV

Question 2

A beam of red light and a beam of violet light each deliver the same power on a surface. For which beam is the number of photons hitting the surface per second the greatest?

A) the red beam
B) the violet beam
C) It is the same for both beams.

Answer 2

the red beam

Question 3

Monochromatic light strikes a metal surface and electrons are ejected from the metal. If the intensity of the light is increased, what will happen to the ejection rate and maximum energy of the electrons?

A) greater ejection rate; same maximum energy
B) same ejection rate; greater maximum energy
C) greater ejection rate; greater maximum energy
D) same ejection rate; same maximum energy

Answer 3

greater ejection rate; same maximum energy

Question 4

A nonrelativistic electron and a nonrelativistic proton have the same de Broglie wavelength. Which of the following statements about these particles are accurate? (There may be more than one correct choice.)

A) Both particles have the same speed.
B) Both particles have the same kinetic energy.
C) Both particles have the same momentum.
D) The electron has more kinetic energy than the proton.
E) The electron has more momentum than the proton.

Question 5

A laser emits light of wavelength 463 nm during a brief pulse that lasts for 25 ms and has a total energy of 1.2 J. How many photons are emitted in that single pulse? (c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34 J ∙ s)

A) 2.8 × 10¹⁸
B) 6.9 × 10¹⁹
C) 3.4 × 10¹⁹
D) 1.1 × 10¹⁷
E) 2.2 × 10¹⁷

Question 6

In a photoelectric effect experiment, electrons emerge from a copper surface with a maximum kinetic energy of 1.10 eV when light shines on the surface. The work function of copper is 4.65 eV. Which one of the following values is closest to the wavelength of the light?
(h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 220 nm
B) 150 nm
C) 360 nm
D) 1100 nm

Question 7

A metal having a work function of 2.8 eV is illuminated with monochromatic light whose photon energy is 3.9 eV. What is the threshold frequency for photoelectron production? (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

A) 6.8 × 10¹⁴ Hz
B) 2.7 × 10¹⁴ Hz
C) 7.6 × 10¹⁴ Hz
D) 8.5 × 10¹⁴ Hz
E) 9.4 × 10¹⁴ Hz

Question 8

Light of wavelength 400 nm falls on a metal surface having a work function 1.70 eV. What is the maximum kinetic energy of the photoelectrons emitted from the metal? (c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34 J ∙ s = 4.141 × 10^-15 ev ∙ s, 1 eV = 1.60 × 10^-19 J)

A) 4.52 eV
B) 3.11 eV
C) 1.41 eV
D) 2.82 eV
E) 1.70 eV

Question 9

A stopping potential of 0.50 V is required when a phototube is illuminated with monochromatic light of wavelength 590 nm. Monochromatic light of a different wavelength is now shown on the tube, and the stopping potential is measured to be 2.30 V. What is the wavelength of this new light? (c = 3.00 × 10⁸ m/s, e = -1.60 × 10^-19 C, h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

A) 320 nm
B) 300 nm
C) 340 nm
D) 360 nm
E) 410 nm

Question 10

Upon being struck by 240-nm photons, a metal ejects electrons with a maximum kinetic energy of What is the work function of this metal? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 3.73 eV
B) 3.13 eV
C) 4.33 eV
D) 4.92 eV

Question 11

A metal surface has a work function of 1.50 eV. Calculate the maximum kinetic energy, in eV, of electrons ejected from this surface by electromagnetic radiation of wavelength 311 nm.
(c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34 J ∙ s, e = -1.60 × 10^-19 C, 1 eV = 1.60 × 10^-19 J)

Question 12

A photon of initial wavelength 0.651 nm, after being scattered from a free electron at rest, moves off at an angle of 120° with respect to its incident direction. (m_el = 9.11 × 10^-31 kg,
h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)
(a) What is the wavelength of the scattered photon?
(b) What is the energy of the scattered photon?

Question 13

An 84-kW AM radio station broadcasts at 1000 kHz. How many photons are emitted each second by the transmitting antenna? (h = 6.626 × 10^-34 J ∙ s)

A) 1.3 ×
B) 2.9 ×
C) 6.3 ×
D) 1.4 ×

Question 14

Gamma rays are photons with very high energy. How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1 × 10^-13 J? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 1.0 × 10⁶
B) 1.4 × 10⁸
C) 6.2 × 10⁹
D) 3.9 × 10³

Question 15

A metal having a work function of 2.5 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm. For which one of the following ranges of the wavelength band in this white light are photoelectrons NOT produced? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 500 nm to 700 nm
B) 400 nm to 560 nm
C) 500 nm to 560 nm
D) 400 nm to 500 nm
E) 560 nm to 700 nm

Question 16

A beam of x-rays at a certain wavelength are scattered from a free electron at rest and the scattered beam is observed at 45.0° to the incident beam. What is the change in the wavelength of the X-rays? (m_el = 9.11 × 10^-31 kg, h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 0.175 pm
B) 0.276 pm
C) 0.000 pm
D) 0.356 pm
E) 0.710 pm

Question 17

A light beam from a 2.1-mW He-Ne laser has a wavelength of 633 nm. How many photons does the laser emit in one second? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 6.7 × 10¹⁵
B) 8.8 × 10¹⁵
C) 1.1 × 10¹⁶
D) 1.3 × 10¹⁶

Question 18

A metal having a work function of 2.4 eV is illuminated with monochromatic light whose photon energy is 4.0 eV. What is the maximum kinetic energy of the photoelectrons produced by this light?

A) 2.6 × 10^-19 J
B) 3.8 × 10^-19 J
C) 4.7 × 10^-19 J
D) 5.5 × 10^-19 J
E) 6.4 × 10^-19 J

Question 19

When a metal surface is illuminated with light of wavelength 437 nm, the stopping potential for photoelectrons is 1.67 V. (c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34 J ∙ s, e = -1.60 × 10^-19 C,
1 eV = 1.60 × 10^-19 J, m_el = 9.11 × 10^-31 kg)
(a) What is the work function of the metal, in eV?
(b) What is the maximum speed of the ejected electrons?

Question 20

In a particular case of Compton scattering, a photon collides with a free electron and scatters backwards. The wavelength after the collision is exactly double the wavelength before the collision. What is the wavelength of the incident photon? (m_el = 9.11 × 10^-31 kg, h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 3.6 pm
B) 4.8 pm
C) 2.4 pm
D) 1.2 pm
E) 6.0 pm

Question 21

A hydrogen atom makes a downward transition from the state to the n = 5 state. Find the wavelength of the emitted photon. The lowest level energy state of hydrogen is -13.6 eV. (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J, c = 3.00 × 10⁸ m/s)

A) 2.43 μm
B) 1.46 μm
C) 1.94 μm
D) 2.92 μm

Question 22

What is the frequency of the light emitted by atomic hydrogen with m = 8 and n = 12? (The Rydberg constant is R = 1.097 × 10⁷ m^-1, ^c = 3.00 × 10⁸ m/s.)

A) 2.86 × 10¹³ Hz
B) 1.43 × 10¹³ Hz
C) 7.46 × 10¹³ Hz
D) 8.82 × 10¹³ Hz
E) 1.05 × 10¹³ Hz

Question 23

The Bohr radius of the hydrogen atom is 0.529 × 10^-10 m. What is the radius of the n = 2 state?

A) 1.06 × 10^-10 m
B) 2.12 × 10^-10 m
C) 0.265 × 10^-10 m
D) 0.529 × 10^-10 m
E) 4.23 × 10^-10 m

Question 24

The energy of the ground state in the Bohr model of the hydrogen atom is -13.6 eV. The energy of the n = 2 state of hydrogen in this model is closest to

A) -3.4 eV.
B) -6.8 eV.
C) -1.7 eV.
D) -13.6 eV.
E) -4.5 eV.

Question 25

A hydrogen atom is in its n = 2 excited state when its electron absorbs a photon of energy . What is the energy of the resulting free electron? The lowest level energy state of hydrogen is -13.6 eV. (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

A) 5.1 eV
B) 6.6 eV
C) 6.9 eV
D) 7.7 eV

Question 26

A photon of wavelength 18.0 pm is scattered through an angle of 120° by a stationary electron. What is the wavelength of the scattered photon? (m_el = 9.11 × 10^-31 kg, h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 19.2 pm
B) 20.4 pm
C) 21.6 pm
D) 22.9 pm
E) 24.1 pm

Question 27

In a double slit experiment, a beam of electrons strikes a pair of slits. The slits are 15 μm apart, and the first interference maximum lies at an angle of 0.50 µrad from the center of the interference pattern. What is the momentum of the incoming electrons? (h = 6.626 × 10^-34 J ∙ s, m_el = 9.11 × 10^-31 kg)

A) 4.4 × 10^-23 kg ∙ m/s
B) 2.2 × 10^-23 kg ∙ m/s
C) 1.1 × 10^-23 kg ∙ m/s
D) 6.6 × 10^-23 kg ∙ m/s
E) 8.8 × 10^-23 kg ∙ m/s

Question 28

A hydrogen atom is excited to the n = 10 stated. It then decays to the n = 4 state by emitting a photon which is detected in a photographic plate. What is the frequency of the detected photon? The lowest level energy state of hydrogen is -13.6 eV. (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

A) 3.46 × 10¹⁴ Hz
B) 0.865 × 10¹⁴ Hz
C) 1.27 × 10¹⁴ Hz
D) 4.05 × 10¹⁴ Hz
E) 1.73 × 10¹⁴ Hz

Question 29

Electrons emerge from an electron gun with a speed of 2.0 × 10⁶ m/s and then pass through a pair of thin parallel slits. Interference fringes with a spacing of 2.7 mm are detected on a screen far from the double slit and fairly close to the center of the pattern. What would the fringe spacing be if the electrons were replaced by neutrons with the same speed? (m_el = 9.11 × 10^-31 kg, m_neutron = 1.67 × 10^-27 kg)

A) 1.5 µm
B) 4.9 µm
C) 0.93 nm
D) 1.1 µm
E) 1.5 nm

Question 30

Calculate the kinetic energy (in eV) of a nonrelativistic neutron that has a de Broglie wavelength of (h = 6.626 × 10^-34 J ∙ s, m_neutron = 1.675 × 10^-27 kg,
1 eV = 1.60 × 10^-19 J)

Question 31

X-rays of energy 2.9 × 10⁴ eV are scattered by a free stationary electron through an angle of 135°. What is the energy of the scattered X-rays, in electron volts? (m_el = 9.11 × 10^-31 kg,
e = - 1.60 × 10^-19 C, h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

Question 32

A hydrogen atom initially in the n = 6 state decays to the n = 2 state. The emitted photon is detected in a photographic plate. What is the wavelength of the detected photon? The lowest level energy state of hydrogen is -13.6 eV. (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J, c = 3.00 × 10⁸ m/s)

A) 410 nm
B) 93.8 nm
C) 1090 nm
D) 93.1 nm

Question 33

The energy of the ground state in the Bohr model of the hydrogen atom is -13.6 eV. In a transition from the n = 2 state to the n = 4 state, a photon of energy

A) 3.40 eV is emitted.
B) 3.40 eV is absorbed.
C) 2.55 eV is emitted.
D) 2.55 eV is absorbed.
E) 0.85 eV is absorbed.

Question 34

Suppose that in a parallel universe, the proton and electron were identical to their counterparts in our own universe EXCEPT that the electron had twice as much charge as our electron. In our present universe, the radius of the first Bohr orbit for hydrogen is a₀ and the speed of an electron in that orbit is v₀. In the parallel universe,
(a) what would be the radius (in terms of a₀) of the first Bohr orbit for hydrogen?
(b) what would be the speed (in terms of v₀) of an electron in the first Bohr orbit for hydrogen?

Question 35

What is the orbital radius of the excited state in the Bohr model of the hydrogen atom? The ground-state radius of the hydrogen atom is 0.529 × 10^-10 m.

A) 0.477 nm
B) 0.159 nm
C) 0.382 nm
D) 0.549 nm

Question 36

How fast must a nonrelativistic electron move so its de Broglie wavelength is the same as the wavelength of a 3.4-eV photon? (m_el = 9.11 × 10^-31 kg, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 2000 m/s
B) 1900 m/s
C) 1700 m/s
D) 1600 m/s
E) 1400 m/s

Question 37

What is the energy of a photon that has a wavelength equal to the de Broglie wavelength of a proton having a speed of 7.1 × m/s? (m_proton = 1.67 × 10^-27 kg, c = 3.00 × 10⁸ m/s)

A) 220 keV
B) 150 keV
C) 290 keV
D) 360 keV
E) 440 keV

Question 38

A photon of wavelength 29 pm is scattered by a stationary electron. What is the maximum possible energy loss of the photon? (m_el = 9.11 × 10^-31 kg, h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s)

A) 4.0 keV
B) 7.0 keV
C) 10 keV
D) 6.1 keV
E) 12 keV

Question 39

Light excites atomic hydrogen from its lowest level to the n = 4 level. What is the energy of the light? The energy of the lowest level is -13.6 eV.

A) 12.8 eV
B) 3.40 eV
C) 0.850 eV
D) 26.4 eV

Question 40

Light shines through atomic hydrogen gas. It is seen that the gas absorbs light readily at a wavelength of 91.63 nm. What is the value of n of the level to which the hydrogen is being excited by the absorption of light of this wavelength? Assume that the most of the atoms in the gas are in the lowest level. (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J, the Rydberg constant is R = 1.097 × 10⁷ m^-1.)

A) 14
B) 16
C) 11
D) 21

Question 41

A gas of helium atoms (each of mass 6.65 × 10^-27 kg) are at room temperature of 20.0°C. What is the de Broglie wavelength of the helium atoms that are moving at the root-mean-square speed? (h = 6.626 × 10^-34 J ∙ s, the Boltzmann constant is 1.38 × 10^-23 J/K)

A) 5.22 × 10^-11 m
B) 7.38 × 10^-11 m
C) 1.04 × 10^-10 m
D) 2.82 × 10^-10 m
E) 3.99 × 10^-10 m

Question 42

A nonrelativistic electron has a kinetic energy of 5.4 eV. What is the energy of a photon whose wavelength is the same as the de Broglie wavelength of the electron? (m_el = 9.11 × 10^-31 kg, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J)

A) 2.4 keV
B) 2.2 keV
C) 2.0 keV
D) 2.5 keV
E) 2.7 keV

Question 43

A single slit is illuminated at normal incidence with a parallel beam of light having a wavelength of The entire central band of the diffraction pattern is observed at ±90°. The illumination is now replaced by a nonrelativistic beam of electrons, each having a kinetic energy of 980 eV. When this beam hits the slit at normal incidence, at what angle will the first minimum of the electron diffraction pattern occur? (h = 6.626 × 10^-34 J ∙ s, m_el = 9.11 × 10^-31 kg, 1 eV = 1.60 × 10^-19 J)

A) 0.095 mrad
B) 0.071 mrad
C) 0.046 mrad
D) 0.12 mrad
E) 0.14 mrad

Question 44

A nonrelativistic electron is accelerated from rest through a potential difference. After acceleration the electron has a de Broglie wavelength of 880 nm. What is the potential difference though which this electron was accelerated? (h = 6.626 × 10^-34 J ∙ s, e = -1.60 × 10^-19 C, m_el = 9.11 × 10^-31 kg)

A) 1.9 µV
B) 1.7 µV
C) 2.2 µV
D) 2.5 µV

Question 45

Light of wavelength 105 nm falls on a metal surface for which the work function is 5.00 eV. What is the minimum de Broglie wavelength of the photoelectrons emitted from this metal? (h = 6.626 × 10^-34 J ∙ s = 4.14 × 10^-15 eV ∙ s, c = 3.00 × 10⁸ m/s, m_el = 9.11 × 10^-31 kg,
1 eV = 1.60 × 10^-19 J)

A) 0.24 nm
B) 0.33 nm
C) 0.47 nm
D) 0.66 nm
E) 0.94 nm