ADDITIONS TO PROBLEMS and PROBLEMS FROM HRW SUPPLEMENT #1
JULY 15 - JULY 21
Correction to HRW CHAPTER 28, #33.
EMF2 in the figure for that problem should be drawn from
the negative side of the battery to the positive side.
Battery EMF's always go from negative to positive.
Problems from HRW Problem Supplement #1 (6th edition)
CHAPTER 25
58. Consider a flat, nonconducting ring of outer
radius R and inner radius r = 0.200R; the ring
has a uniform charge per unit area of sigma.
With V = 0 at infinity, find an expression for
the electric potential at point P on the central
axis of the ring, at a distance z = 2.00R from
the center of the ring.
CHAPTER 26
53. A certain parallel-plate capacitor is filled with
a dielectric for which Kappa = 5.5. The area of
each plate is 0.034 m^2, and the plates are
separated by 2.0 mm. The capacitor will fail
(short out and burn up) if the electric field
between the plates exceeds 200 kN/C. What is the
maximum energy that can be stored in the capacitor?
66. Two parallel-plate capacitors A and B are connected
in parallel across a 600 V battery. Each plate has
area 80.0 cm^2 and the plate separations are 3.0 mm.
Capacitor A is filled with air; capacitor B is
filled with a dielectric of dielectric constant
Kappa = 2.60. Find the magnitude of the electric
field within (a) the dielectric of capacitor B and
(b) the air of capacitor A. What are the free
charge densities sigma on the higher-potential
plate of (c) capacitor A and (d) capacitor B?
(e) What is the induced charge density sigma' on
the surface of the dielectric which is nearest to
the higher-potential plate of capacitor B.
74. The figure for this problem is Fig. 26-17, with
the dielectric in that figure being replaced with
a piece of copper. A slab of copper of thickness
b is thrust into a parallel-plate capacitor of
plate area A; it is exactly halfway between the
plates. (a) What is the capacitance after the
slab is introduced? (b) If a charge q is
maintained on the plates, what is the ratio of
the stored energy before to that after the slab
is inserted? (c) How much work is done on the
slab as it is inserted? Is the slab sucked in
or must it be pushed in?