Document 6534808

1. The work function for a certain sample is 2.3 eV. The stopping potential for electrons ejected from the
sample by 7.0 × 1014-Hz electromagnetic radiation is:
A. 0
B. 0.60 V
C. 2.3 V
D. 2.9 V
E. 5.2 V
2. The ground state energy of a hydrogen atom is –13.6 eV. The energy of the first excited state is:
A. 0
B. –3.4 eV
C. –6.8 eV
D. –9.6 eV
E. –27 eV
3. y (x ) is the wave function for a particle moving along the x axis. The probability that the particle is in the
interval from x = a to x = b is given by:
A. y(b) – y(a)
B. çy(b)ç2 – çy(a)ç2
C. çy(b) – y(a)ç2
D.
E.
4. A photon in light beam A has twice the energy of one in light beam B. The ratio lA/lB of the wavelengths
is:
A. 1/2
B. 1/4
C. 1
D. 2
E. 4
5. An electron with energy E is incident on a potential energy barrier of height Epot and thickness L. The
probability of tunneling increases if:
A. E decreases without any other changes
B. Epot increases without any other changes
C. L decreases without any other changes
D. E and Epot increase by the same amount
E. E and Epot decrease by the same amount
6. A particle is trapped in a one-dimensional well with infinite potential energy at the walls. Three possible
pairs of energy levels are
1. n = 3 and n = 1
2. n = 3 and n = 2
3. n = 4 and n = 3
Order these pairs according to the difference in energy, least to greatest.
A. 1, 2, 3
B. 3, 2, 1
C. 2, 3, 1
D. 1, 3, 2
E. 3, 1, 2
7. Rank following electromagnetic radiations according to the energies of their photons, from least to
greatest.
1. blue light
2. yellow light
3. x-rays
4. radio waves
A. 1, 2, 3, 4
B. 4, 2, 1, 3
C. 4, 1, 2, 3
D. 3, 2, 1, 4
E. 3, 1, 2, 4
8. The ground state energy of an electron in a one-dimensional trap with zero potential energy in the interior
and infinite potential energy at the walls is 2.0 eV. If the width of the well is doubled, the ground state
energy will be:
A. 0.5 eV
B. 1.0 eV
C. 2.0 eV
D. 4.0 eV
E. 8.0 eV
9. Consider the following three particles:
1. a free electron with kinetic energy K0
2. a free proton with kinetic energy K0
3. a free proton with kinetic energy 2K0
Rank them according to the wavelengths of their waves, least to greatest.
A. 1, 2, 3
B. 3, 2, 1
C. 2, 3, 1
D. 1, 3, 2
E. 1, then 2 and 3 tied
10. An electron is in a one-dimensional trap with zero potential energy in the interior and infinite potential
energy at the walls. The ratio E3/E1 of the energy for n = 3 to that for
n = 1 is:
A. 1/3
B. 1/9
C. 3/1
D. 9/1
E. 1/1
11. An electron in an atom initially has an energy 7.5 eV above the ground state energy. It drops to a state
with an energy of 3.2 eV above the ground state energy and emits a photon in the process. The
momentum of the photon is:
A. 1.7 × 10–27 kg × m/s
B. 2.3 × 10–27 kg × m/s
C. 4.0 × 10–27 kg × m/s
D. 5.7 × 10–27 kg × m/s
E. 8.0 × 10–27 kg × m/s
12. If the kinetic energy of a non-relativistic electron doubles, the wavelength of its wave function changes by
the factor:
A.
B. 1/2
C. 1/4
D.
E. 2
13. Monoenergetic electrons are incident on a single slit barrier. If the energy of each incident electron is
increased the central maximum of the diffraction pattern:
A. widens
B. narrows
C. stays the same width
D. widens for slow electrons and narrows for fast electrons
E. narrows for slow electrons and widens for fast electrons
14. The diagram shows the energy levels for an electron in a certain atom. Of the transitions shown, which
represents the emission of a photon with the most energy?
A. I
B. II
C. III
D. IV
E. V
15. The diagram shows the graphs of the stopping potential as a function of the frequency of the incident light
for photoelectric experiments performed on three different materials. Rank the materials according to the
values of their work functions, from least to greatest.
A. 1, 2, 3
B. 3, 2, 1
C. 2, 3, 1
D. 2, 1, 3
E. 1, 3, 2
16. Identical particles, each with energy E, are incident on the following four potential energy barriers:
1. barrier height = 5E, barrier width = 2L
2. barrier height = 10E, barrier width = L
3. barrier height = 17E, barrier width = L/2
4. barrier height = 26E, barrier width = L/3
Rank the barriers in terms of the probability that the particles tunnel through them, from least probability
to greatest probability.
A. 1, 2, 3, 4
B. 4, 3, 2, 1
C. 1 and 2 tied, then 3, then4
D. 2, then 2 and 3 tied, then 4
E. 3, 2, 1, 4
17. In Compton scattering from stationary electrons the largest change in wavelength occurs when the photon
is scattered through:
A. 0°
B. 45°
C. 90°
D. 180°
E. 270°
18. Two one-dimensional traps have infinite potential energy at their walls Trap A has width L and trap B has
width 2L. For which value of the quantum number n does a particle in trap B have the same energy as a
particle in the ground state of trap A?
A. n = 1
B. n = 2
C. n = 3
D. n = 4
E. n = 5
19. Electromagnetic radiation with a wavelength of 5.7 × 10–12 m is incident on stationary electrons. The
radiation that has been scattered through 50° has a wavelength of:
A. 2.43 × 10–12 m
B. 4.83 × 10–12 m
C. 5.13 × 10–12 m
D. 6.27 × 10–12 m
E. 6.57 × 10–12 m
20. An electron in an atom initially has an energy 5.5 eV above the ground state energy. It drops to a state
with energy 3.2 eV above the ground state energy and emits a photon in the process. The wave
associated with the photon has a frequency of:
A. 5.6 × 1014 Hz
B. 1.0 × 1015 Hz
C. 1.8 × 1015 Hz
D. 2.6 × 1015 Hz
E. 2.9 × 1015 Hz