SAT Physics Subject Test
Chapter 16 Modern Physics
Chapter 16 Review Questions
See Chapter 17 for solutions.
1. Which of the following best approximates the energy of a photon whose wavelength is 2.0 nm? (Planck”s constant, h, has a value of 6.6 × 10–34 J • s.)
(A) 4 × 10–51 J
(B) 1 × 10–34 J
(C) 1 × 10–16 J
(D) 1 × 1034 J
(E) 2 × 10–50 J
2. A metal whose work function is 6.0 eV is struck with light of frequency 7.2 × 1015 Hz. What is the maximum kinetic energy of photoelectrons ejected from the metal”s surface?
(A) 7 eV
(B) 13 eV
(C) 19 eV
(D) 24 eV
(E) No photoelectrons will be produced.
3. An atom with one electron has an ionization energy of 25 eV. How much energy will be released when the electron makes the transition from an excited energy level, where E = –16 eV, to the ground state?
(A) 9 eV
(B) 11 eV
(C) 16 eV
(D) 25 eV
(E) 41 eV
4. The single electron in an atom has an energy of –40 eV when it”s in the ground state, and the first excited state for the electron is at –10 eV. What will happen to this electron if the atom is struck by a stream of photons, each of energy 15 eV?
(A) The electron will absorb the energy of one photon and become excited halfway to the first excited state, then quickly return to the ground state, without emitting a photon.
(B) The electron will absorb the energy of one photon and become excited halfway to the first excited state, then quickly return to the ground state, emitting a 15 eV photon in the process.
(C) The electron will absorb the energy of one photon and become excited halfway to the first excited state, then quickly absorb the energy of another photon to reach the first excited state.
(D) The electron will absorb two photons and be excited to the first excited state.
(E) Nothing will happen.
5. What is the de Broglie wavelength of a proton whose linear momentum has a magnitude of 3.3 × 10–23 kg • m/s ?
(A) 0.0002 nm
(B) 0.002 nm
(C) 0.02 nm
(D) 0.2 nm
(E) 2 nm
6. Compared to the parent nucleus, the daughter of a β– decay has
(A) the same mass number but a greater atomic number
(B) the same mass number but a smaller atomic number
(C) a smaller mass number but the same atomic number
(D) a greater mass number but the same atomic number
(E) None of the above
7. The reaction 
is an example of what type of radioactive decay?
(A) alpha
(B) β–
(C) β+
(D) electron capture
(E) gamma
8. Tungsten-176 has a half-life of 2.5 hours. After how many hours will the disintegration rate of a tungsten-176 sample drop to 
its initial value?
(A) 5
(B) 8.3
(C) 10
(D) 12.5
(E) 25
9. What”s the missing particle in the following nuclear reaction?
(A) Proton
(B) Neutron
(C) Electron
(D) Positron
(E) Deuteron
10. What”s the missing particle in the following nuclear reaction?
(A) Proton
(B) Neutron
(C) Electron
(D) Positron
(E) Gamma
11. Two spaceships are traveling directly toward each other, one traveling at a speed of 
and the other at a speed of 
, as measured by observers on a nearby planet. The faster ship emits a radar pulse directed toward the approaching ship. What is the speed of this radar pulse, as measured by observers on the planet?
(A) 
(B) 
(C) c
(D) 
(E) 
12. An Imperial battle cruiser, sitting in a hanger deck, is measured to have a length of 200 m by a worker on the deck. If the cruiser travels at a speed of 
c past a planet, what will be the length of the cruiser, as measured by the inhabitants of the planet?
(A) 0
(B) Between 0 and 200 m
(C) 200 m
(D) Greater than 200 m
(E) None of the above, since it is impossible to reach the described speed
13. An astronaut lives on a spaceship that is moving at a speed of 
c away from the earth. As measured by a clock on the spaceship, the time interval between her maintenance checks on the ship”s main computer is 15 months. In the reference frame of the team here on Earth that monitors the ship”s progress, what is the time interval between maintenance checks on the ship”s main computer?
(A) Always less than 15 months
(B) Always exactly 15 months
(C) Always more than 15 months
(D) Initially less than 15 months, but after time more than 15 months
(E) Initially more than 15 months, but after time less than 15 months
14. A particle whose rest energy is E is traveling at a speed of 
c. What is the particle”s kinetic energy?
(A) 
(B) 
(C) 
(D) 
(E) 
15. Redshift of distant galaxies is evidence for which of the following?
(A) Expansion of the universe
(B) The Uncertainty Principle
(C) Black holes
(D) Dark matter
(E) Superconductivity
16. Which of the following is NOT a correct pairing of physicist and field in which he made significant contributions?
(A) Newton — gravitation
(B) Einstein — relativity
(C) Faraday — electricity and magnetism
(D) Coulomb — quantum mechanics
(E) Bohr — atomic structure
17. The impossibility of making simultaneous, arbitrarily precise measurements of the momentum and the position of an electron is accounted for in
(A) thermodynamics
(B) quantum mechanics
(C) classical electrodynamics
(D) special relativity
(E) general relativity
Keywords
raisin pudding model
alpha particles
Rutherford nuclear model
quanta
photon
photoelectric effect
photoelectrons
threshold frequency
Planck”s constant
work function
electronvolt (eV)
atomic spectra
excited
energy level
quantized
wave–particle duality
de Broglie wavelength
protons
neutrons
nucleons
atomic number
neutron number
mass number
nucleon number
isotopes
nuclide
strong nuclear force
atomic mass unit (amu)
dueteron
deuterium
mass defect
binding energy
mass–energy equivalence
radioactive
alpha
beta (β)
gamma
parent
daughter
electron capture (Ec)
beta particle
electron-antineutrino
weak nuclear force
positron
antiparticle
electron-neutrino
gamma ray
decay constant
activity
becquerel (Bq)
half-life
exponential decay
nuclear fission
nuclear fusion
disintegration energy
exothermic
endothermic
inertial reference frame
relativistic factor
length contraction
rest energy
total energy
general relativity
Equivalence Principle
precession of Mercury
gravitational time dilation
black hole
quasar
expansion of the universe
electron microscope
Heisenberg Uncertainty Principle
superconductor
weak nuclear force
Cosmic Microwave Background
dark matter
dark energy
Summary
For the test, be sure you are familiar with the following concepts from this chapter.
· Rutherford model of the atom
· Photons and the photoelectric effect
· The Bohr model of the atom
· Wave–particle duality
· Nuclear physics
· The nuclear force
· Binding energy
· Radioactivity
· Alpha decay
· Beta decay
· β– decay
· β+ decay
· Electron capture
· Radioactive decay rates
· Nuclear reactions
· Disintegration energy
· Special relativity
· The relativity of velocity
· The relativity of time
· The relativity of length
· Relativistic energy
In addition, be able to describe the following briefly:
· General relativity
· Quantum mechanics
· Current problems in physics and astronomy