# SAT Physics Practice Test: Modern Physics

### Test Information

17 questions

13 minutes

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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

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