Class Notes V to IX [Conservation Laws, Solar Neutrinos, Quantum
Mechanics, Quarks etc., Discrete Symmetries]
Review Questions For 146 Exam 2
Is there any limit to the accuracy of measurement of a position?
Is there any limit to the accuracy of measurement of a velocity?
Is there any limit to the accuracy of simultaneous measurement
of position and velocity?
Is light composed of waves?
Is light composed of particles?
What, according to quantum mechanics, is the physical meaning
of light waves?
Can an electron interfere with itself? Does this question even
make sense?
In the double-slit experiment, how can you tell which slit an
electron passes through?
Can the electron in a hydrogen atom occupy an arbitrary orbit
around the proton? If not, why not?
What is a wave?
Does a wave necessarily move in the same direction as the
objects in the medium?
What happens if two waves cross each other?
Can light projected onto a screen get fainter and fainter
without limit?
What can you predict about the location a photon will arrive on
a screen in the double-slit experiment?
How do two electrons exert electric forces on each other?
Given that a sphere has an area of 4 pi R*R, where R is its
radius, how does the strength of electric forces vary with distance
between the particles? Why?
Assume that astrophysicists understand the generation of heat
in the sun. How can you explain the small number of observed solar
neutrinos?
How is energy generated in the sun?
How could we determine for sure the rate of nuclear reactions
in the sun?
Is it true that an atom can be in only one state at a time?
Can the spin of a particle point in a definite direction?
Given the spins of two particles, can you always predict what
the spin of a combination of the two will be? If not, why not?
Given the spins of two particles, is there any limit on what
the spin of a combination of the two can be? If so, where does the
limit come from?
How do you recognize that a pair of charged particles are a
particle/antiparticle pair?
How do you recognize that a pair of uncharged particles are a
particle/antiparticle pair?
Does every particle have an antiparticle? Explain.
How do you determine if a particle is a lepton?
How do you determine if a particle is a baryon?
How do you determine if a particle is a meson?
Are the force-carrying particles classified as leptons, baryons,
or mesons? [They are one of the three, but which one?].
Are all mesons (baryons, leptons) force carrrying particles?
Why do we believe that all baryons and most mesons are composed of
quarks and/or antiquarks?
How many valence quarks are there in a baryon? How many valence
antiquarks?
How many valence quarks are there in a meson? How many valence
antiquarks?
The Omega- baryon (charge = -1) contains three strange
quarks. What is the charge of a strange quark? Explain.
The proton contains two up quarks and one down quark. The
neutron contains one up quark and two down quarks. What are the
charges of these two quarks? Explain.
Is the spin of a quark a half-integer [1/2, 3/2, ...] or an
integer? How do you know?
In the decay N -> P + e- + anti-electron-neutrino,
what happens in terms of the quarks?
What does the parity operation do to positions? to B? to L? to
time? to velocity?
What does time reversal do to positions? to B? to L? to time?
to velocity?
What does charge conjugation do to positions? to B? to L? to
time? to velocity?
What forces are unchanged under parity? under time reversal?
under charge conjugation? under the product of all three?
Suppose one symmetry operation reverses both position and time,
and another reverses only time. What does the product of the two
operations do to position and time?
How do you form the product of two symmetry operations?
Which of parity, time reversal, and charge conjugation changes
the spin of a particle? In what way is the spin changed?
What is the preferred assumption about the relative number of
particles and their antiparticles at the time of the Big Bang?
Does data indicate that the density of baryons is currently
equal to the density of antibaryons? What about leptons and
antileptons?
Is esthetics completely irrelevant to science?
What do you decide if a strong esthetic argument conflicts with
reliable experimental data?
Why is the tiny breaking of CP-invariance important?
What does it mean when a physicist says that something is
conserved?
What is a selection rule?
What are B and L?
What quantities are always conserved in Particle Physics?
What are the allowed values of charge for ordinary particles?
For quarks? [Give values as a number times the charge of the proton.]
Is charge ever negative?
What is the value of lepton number for an antilepton?
What is the value of baryon number for an antibaryon?
Does the reaction photon -> e+ +
e- conserve lepton number? baryon number?
Does the reaction photon -> proton + anti-proton conserve
lepton number? baryon number?
How is charge related to hypercharge?
How is charge related to isospin?
What is the evidence for the existance of isospin?
The baryons included in our Particle Table all fit into two
SU(3) multiplets. The mesons fit into two multiplets (not necessarily
the same size). How many baryons are in the table? How many mesons?
There exist a Xi- and a Xi0; no other
baryons have similar masses. What is the isospin and hypercharge of
the Xi baryons?
Are strangeness and hypercharge conserved?
Is there a selection rule for strangeness?
What is the most impressive esthetic argument for SU(3)
multiplets being a useful classification of particles?
How many quarks are involved in SU(3)? How many quarks are
there altogether?
A given pi-meson is made up of a d and an anti-u quark. What
is the charge, hypercharge, and baryon number of that pi, and why?
Is this particle a pi+, pi0, or pi-?