Modern Physics Practice Unit Exam

1. The threshold frequency of a metal surface is in the violet light region. What type of radiation will
cause electrons to be emitted from the metal's surface ?
infrared light red light ultraviolet light radio waves

2. Which formula may be used to compute the energy of a photon ?
E = hf E = mgh E = 1/2 mv2 E = Fs

3. In a photon-electron collision, there is conservation of
mass energy only momentum only energy and momentum

4. Rutherford's model of the atom showed that most of the atom's volume is composed of
protons electrons neutrons empty space

5. What is the minimum energy needed to ionize a hydrogen atom when it is in the n = 2 state ?
1.9 eV 3.4 eV 12.2 eV 13.6 eV

6. A hydrogen atom emits a photon with an energy of 1.63 x 10-18 J as it changes to the ground state.
The radiation emitted by the atom would be classified as
infrared ultraviolet blue light red light

7. If only the frequency of light falling on a metal surface increases, the rate of particle emission will
decrease increase remain the same

8. If only the intensity of light falling on a metal surface increases, the energy of each emitted electron will
decrease increase remain the same

9. All of the following particles are traveling at the same speed. Which has the greatest wavelength ?
proton alpha particle neutron electron

10. Compared to the energy of photons of blue light, the energy of photons of red light is
less greater the same

11. When incident on a given photoemissive surface, which color of light will produce electrons with the
greatest energy ?
red orange violet green

12.  In a collision between an x-ray photon and an electron, which of the following is conserved ?
energy momentum energy and momentum

13. In the Balmer series, during which of the following energy state changes of the hydrogen atom is the photon
with the most energy emitted ?
n = 5 to n = 2 n = 4 to n = 2 n = 2 to n = 4 n = 2 to n = 5

14. Compared to the frequency of 3.0 eV photons, the frequency of 2.0 eV photons is
lower higher the same

15. What is the minimum energy needed to ionize a hydrogen atom when it is in the n = 2 state ?
1.9 eV 3.4 eV 12.2 eV 13.6 eV

16. Blue light has a frequency of 6.0 x 1014 Hz. A photon of blue light will have an energy of
1.1 x 10-48 J  6.0  x 10-34 J  5.0  x 10-7 J 4.0  x 10-19 J

17. Which phenomenon can only be explained by assuming that light is quantized ?
polarization  diffraction  interference photoelectric effect

18. The ratio of the energy of a quantum of electromagnetic radiation to its frequency is
the electrostatic constant  the electronvolt  the gravitational constant Planck's constant

19. As the momentum of a particle increases, its matter wavelength
decreases  increases  remains the same

20. As the wavelength of a photon decreases, its momentum
decreases  increases  remains the same

21. When an electron changes from a higher energy state to a lower energy state within an atom, a photon is
fissioned  fused  emitted absorbed

22. A hydrogen atom in the ground state receives 10.2 eV of energy. To which energy level may the
atom become excited ?
n = 5  n = 2  n = 3 n = 4

23. A beam of blue light causes electrons to be emitted from a photoemissive surface. An increase in the intensity
of the blue light will cause an increase in the
maximum KE of the emitted electrons  number of electrons emitted per unit of time
  charge carried by each electron work function of the photoemissive surface

24. Which type of force causes the hyperbolic trajectory of alpha partcles in Rutherford's scattering experiment ?
gravitational electrostatic magnetic nuclear

25. An electron in a mercury atom that is changing from the "a" to the "g" level absorbs a photon with an energy of
12.86 eV  10.38 eV  7.90 eV 2.48 eV

26. The momentum of a photon with a wavelength of 5.9 x 10-7 m is
8.9 x 1026 kg*m/s  1.6 x 10-19 kg*m/s  1.1 x 10-27 kg*m/s 3.9 x 10-40 kg*m/s

27. Which phenomenon provides evidence that atoms have discrete energy levels ?
radioactive decay alpha-particle scattering photoelectric effect emission spectra

28. A photon emitted from an excited hydrogen atom has an energy of 3.02 eV. Which electron energy-level
transition would produce this photon ?
n = 1 to n = 6  n = 2 to n = 6  n = 6 to n = 1 n = 6 to n = 2

29. According to the Bohr atomic model, if an orbiting electron falls to a lower orbit, the total energy of that atom will
decrease  increase  remain the same

30. Compared to the photon momentum of blue light, the photon momentum of red light is
less  greater  the same

31.Which particles are most likely to be found in an atomic nucleus ?
neutrons only   protons only   both protons and neutrons both neutrons and electrons

32.Which statement most accurately describes the interaction which binds a nucleus together ?
long-range and weak   long-range and strong   short-range and weak short-range and strong

33.One universal mass unit is defined as
the mass of an electron   the mass of a proton
  the mass of a carbon-12 atom 1/12 the mass of carbon-12 atom

34.If the mass of one proton was totally converted into energy, the yield would be
2.79 x 10-38 J   5.01 x 10-19 J   1.50 x 10-10 J 9.00 x 1016 J

35.A baryon may have a charge of
-1/3 e   0 e   +2/3 e +4/3 e

36.An antibaryon is composed of
3 quarks   1 quark and 2 antiquarks   3 antiquarks 2 quarks and 1 antiquark

37.A particle has a quark composition of dds. What is the charge on and classification of the particle ?
-1 e, baryon   +1 e, baryon   -1 e, meson +1 e, meson

38.The electron is classified as a
baryon   lepton   meson quark

39.Protons and neutrons are examples of
positrons   baryons   mesons quarks

40.If a deuterium nucleus has a mass of 1.53 x 10-3 universal mass units less than its components,
this mass represents an energy of
1.38 MeV   1.42 MeV   1.53 MeV 3.16 MeV