1. Which of the following statements is correct?
(A) If a gaussian surface contains zero net charge, the electric field at
every location on the surface must be zero.
(B) If net flux through a gaussian surface is zero, the surface must
enclose no charge.
(C) If the electric field at every location on a gaussian surface is zero,
the surface must contain no net charge.
(D) The electric field on a gaussian surface is generally not influenced
by charge that is not enclosed by the surface.
(E) Charges outside the gaussian surface affect the electric field on the
surface and therefore affect the net flux through the surface.
2. A spherical metal shell with zero net charge encloses a point charge.
The magnitude of the surface charge density
(A) is greater on the outside surface of the shell than on the inside
surface of the shell
(B) is greater on the inside surface of the shell than on the outside
surface of the shell
(C) is zero because the net charge is zero
(D) is zero because the surface charge density of a metal must be zero
(E) Not enough information is given.
3. Two metal spherical shells, with radii r1 > r2, each contain a charge +Q
distributed on their metal surfaces. The two shells are located far apart
from each other compared to their radii. When a wire connects the two
shells, what happens?
(A) Negative charge flows from sphere 1 to sphere 2.
(B) Negative charge flows from sphere 2 to sphere 1.
(C) No charge flows between the spheres.
(D) An electric field builds with time within the wire.
(E) No magnetic fields are produced.
4. Referring to the situation described in question 3 after the two spheres
reach equilibrium, what is the ratio of their charges (assuming
negligible charge accumulates on the wire)?
(A) Q1/Q2 = r1/r2
(B) Q1/Q2 = r2/r1
(C) Q1/Q2 = (r1/r2)2
(D) Q1/Q2 = (r2/r1)2
(E) none of the above
5. A point charge −Q is inserted inside a cubic uncharged metal box.
Which of the following statements is true?
(A) A net charge of +Q is distributed on the inner surface of the box.
(B) The electric field outside the box is unaffected by the box and is
determined solely by the point charge.
(C) The potential within the walls of the metal box is zero.
(D) There is a net charge of +Q on the box.
(E) The electric field inside the region bounded by the metal box is
zero.
6. Suppose that two concentric spherical shells with radii r1 < r2 contain
net charges Q2 > 0 and Q1 = −Q2. In Figure 13.4 which graph is a plot
of the electric field as a function of radial position? (Defining away
from the center as positive.)