ASSIGNMENT #11
DUE ON NOVEMBER 24, 2005
HAND-IN
CHAPTER #28:
QUESTIONS:
8 Particle roundabout. Figure 28-31 shows 11 paths through a region of uniform magnetic field. One path is a straight line; the rest are half-circles. Table 28-4 gives the masses, charges, and speeds of 11 particles that take these paths through the field in the directions shown. Which path in the figure corresponds to which particle in the table?
PROBLEMS:
14 Figure 28-36 shows a metallic block, with its faces parallel to coordinate axes. The block is in a uniform magnetic field of magnitude 0.020 T. One edge length of the block is 25 cm; the block is not drawn to scale. The block is moved at 3.0 m/s parallel to each axis, in turn, and the resulting potential difference V that appears across the block is measured. With the motion parallel to the y axis, V = 12 mV; with the motion parallel to the z axis, V = 18 mV; with the motion parallel to the x axis, V = 0. What are the block lengths (a) dx, (b) dy, and (c) dz?
41
Figure 28-42
shows a wire ring of radius a = 1.8 cm that is perpendicular to the
general direction of a radially symmetric, diverging magnetic
field. The magnetic field at the ring is everywhere of the same
magnitude B = 3.4 mT, and its direction at the
ring everywhere makes an angle 
with a normal
to the plane of the ring. The twisted lead wires have no effect on the problem.
Find the magnitude of the force the field exerts on the ring if the ring
carries a current
i = 4.6 mA.
71 In Figure 28-53, a metal wire of mass m = 24.1 mg can slide with negligible friction on two horizontal parallel rails separated by distance d = 2.56 cm. The track lies in a vertical uniform magnetic field of magnitude 56.3 mT. At time t = 0, device G is connected to the rails, producing a constant current i = 9.13 mA in the wire and rails (even as the wire moves). At t = 61.1 ms, what are the wire's (a) speed and (b) direction of motion (left or right)?
82 A beam of electrons whose kinetic energy is K
emerges from a thin-foil window at the end of an accelerator tube. A metal
plate at distance d from this window is perpendicular to the direction
of the emerging beam (Figure 28-55).
(a) Show that we can prevent the beam from hitting the plate if we apply a
uniform magnetic field 
such
that
in which m
and e are the electron mass and charge. (b) How should be
oriented?
CHAPTER #31:
QUESTIONS:
PROBLEMS:
33
An ac generator has emf 
, where 
and 
. The current produced in a connected circuit
is 
, where Io = 620 mA.
At what time after t = 0 does (a) the generator emf
first reach a maximum and (b) the current first reach a maximum? (c) The
circuit contains a single element other than the generator. Is it a capacitor,
an inductor,
or a resistor? Justify your answer. (d) What is the value of the capacitance,
inductance,
or resistance,
as the case may be?
ONLINE
CHAPTER #28:
QUESTIONS:
PROBLEMS:
12 A strip of copper 
thick and 4.5
mm wide is placed in a uniform magnetic field of
magnitude 0.65 T, with perpendicular
to the strip. A current i = 23 A is
then sent through the strip such that a Hall potential
difference V appears across the width of the strip. Calculate
V. (The number of charge carriers per unit volume for copper is 8.47 Χ
1028 electrons/m3.)
23
A positron with kinetic energy 2.00 keV is projected
into a uniform magnetic field of
magnitude 0.100 T, with its velocity vector making an angle of 89.0° with .
Find (a) the period, (b) the pitch p, and (c) the radius r of its
helical path.
CHAPTER #31:
QUESTIONS:
PROBLEMS:
30
A 
resistor
is connected as in Figure 31-8a
to an ac generator with 
m
= 30.0 V. What is the amplitude of the resulting alternating current
if the frequency of the emf is (a) 1.00 kHz and (b)
8.00 kHz?
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