Test #3    Physics 262       Chapt 39,40,41, 43          SOLUTIONS

                                       

                                                                  

  1. A photon is ________________.
    1. a quantum of electromagnetic energy
    2. an oscillating electron
    3. light wave with a short wavelength
    4. a very small hard ball like an electron (but without charge)

 

  1. The energy carried by a single photon
    1. cannot be calculated
    2. is proportional to the frequency of the radiation
    3. is proportional to the speed of the photon
    4. is not any fixed amount for any given color 

 

  1. The Planck Constant, h, is                 (h = 6.63 x 10-34 Js)
    1. to adjust energies for the uncertainty principle
    2. the constant involved in all quantum equations (in our system of units)
    3. changes for different particles
    4. ties together energy and distance

 

  1. De Broglie suggested that
    1. a period chart of elements could be figured out
    2. moving matter has a wavelength associated with it
    3. the wavelength of matter depended on its dimensions
    4. atoms have a nucleus and electrons

 

  1. The de Broglie wavelength of a proton moving at 4000 m/s is (mp = 1.67 x 10-27 Kg)
    1. 6.68 nM
    2. 99.3 pM
    3. 13.3 microns
    4. 1.68 nM

 

 

 

 

  1. To be more precise, we should say that light and very small particles are really __________ between where they are generated and where they are detected
    1. there all the time.
    2. in another dimension
    3. probability waves
    4. non-existent

 

  1. Schroedinger’s Euqation is used to calculate ________________.
    1. probability densities
    2. wave functions
    3. wave paths
    4. particle positions

 

  1. The wave function,  y(x,t), tells us
    1. nothing
    2. probability densities
    3. the uncertainty of a wave position
    4. nothing, unless we square it

 

  1. An electron in an electrostatic potential well
    1. can easily escape
    2. will fall to the bottom and lose all its energy
    3. has to have a quantized energy level
    4. can have any energy

 

  1. Transitions of an electron between energy levels in an atom
    1. will absorb or give off a photons
    2. will absorb or give off an x-rays
    3. are possible only if the atom is free in space
    4. cannot take place in a potential well 

 

  1. The energy levels in atomic hydrogen are inversely proportional to
    1. Planck’s constant (squared)
    2. the mass of the elctron
    3. the mass of the nucleus
    4. the charge on the electron

 

  1.   What did DeBroglie add to the Bohr theory of the atom?
    1. the lengths of the orbit circumferences
    2. the mass needed in the nucleus to give a matter wave 
    3. the wavelength of the radius of the nucleus
    4. a list of the wavelengths that could be emitted by the atom
  2.  An electron in a d subshell of an atom can have orbital and ______ angular momentum
    1. no other
    2. spin
    3. cannot have any orbital angular momentum
    4. atomic

 

  1.   The orbital dipole magnetic moment is
    1. the same as the Bohr Magneton
    2. depends on the value of l
    3. dependent on the value of ml                  (also acceptable as answer)
    4. only present in the Bohr model of Hydrogen

 

  1.   The number of quantum indices needed to fully specify the energy of an electron in     an atom is:
    1. One
    2. Two
    3. Three
    4. Four
    5. Depends on how many electrons in the atom

 

  1.   A plot of the characteristic K line x-rays from different elements, tells us
    1. the energy of the nucleus
    2. that some elements are radioactive
    3. the atomic numbers of the elements
    4. the atomic masses of the elements

 

  1.  In order to work, a laser must have a material in its cavity that will
    1. give off a bright light when struck by electrons   (also accepted—error on practice exam)
    2. bounce back and forth between the mirrors
    3. has a DeBroglie wavelength
    4. allow pumping to invert the populations in two of its levels

 

  1.  We say that laser light is coherent, meaning that all of the photons in the beam
    1. are the same wavelength, with random phases
    2. are the same polarization, but at different frequencies
    3. have the same phase, frequency, and polarization
    4. have random polarizations, but the same phase, and frequency

 

 

 

  1.  The coherence length of a laser beam is in the length range of
    1. microns
    2. millimeters
    3. meters     I consider this to be a better answer
    4. kilometers   Also acceptable—see text p 1026
    5. infinitely long

 

  1.   The atomic number of an element tells us
    1. the number of protons in the nucleus
    2. the number of neutrons in the nucleus
    3. the number of neutrons plus protons in the nucleus
    4. the number of electrons in the nucleus

 

  1.  The nucleus is only about __________ the size of an atom.
    1. one third
    2. one tenth
    3. one ten thousandth    (linear)
    4. one millionth

 

  1.   An isotope of an element is
    1. the same atom with an opposite charge
    2. has the same number of protons, but different numbers of neutrons
    3. has the same number of neutrons, but different numbers of protons
    4. the same mass with a different number of neutrons
    5. a baseball team in the southwest  

 

  1.   In the process of radioactive decay
    1. nucleons give off radio waves
    2. nucleons explode giving off radiation
    3. nucleons can tunnel through the strong force barrier
    4. nucleons transform from positive to negative

 

  1.   The neutrino
    1. has not been detected yet
    2. is the heaviest known particle
    3. has no mass
    4. is extremely difficult to detect

 

  1.   A beta ray is actually
    1. an x ray photon
    2. an electron
    3. a proton
    4. a neutron

 

  1.   Radioactive dating
    1. works only on things containing uranium or carbon
    2. uses isotope comparisons
    3. uses the detection and counting of radioactive decays
    4. is a new reality show

 

  1.   Nuclei have discrete energy levels just like electrons in atoms.
    1. true
    2. false
    3. only for less massive elements
    4. only for more massive elements

 

  1.   The three common forms of radioactivity are
    1. x ray,  gamma ray, beta ray
    2. alpha, beta, gamma
    3. alpha, beta, neutrino
    4. beta, gamma, delta

 

  1.   Calculate the third energy level for a neutron in an infinitely deep one dimensional potential well of width 1.0 fempto-Meter.    mn = 1.68 x 10-27 Kg
    1. 14 Mev
    2. 37 Mev
    3. 52 Mev
    4. 89 Mev
    5. 184 Mev   Error on answer—should be 1840 MeV

 

     30.  Mark the same answer

       as you had for (29) on

       the blue answer sheet

 

     31.  Mark the same answer

  as you had for (29) on

  the blue answer sheet

 

 

 

 

 

 

 

More on next page.

 

  1.  Calculate the wavelength for a frequency of 173 MHz.
    1. 0.39 M
    2. 1.73 M
    3. 5.19 M
    4. 5.77 M
    5. 17.3 M

 

End of Test 3.   Comments on this test: J