ANSWERS TO EVEN NUMBERED PROBLEMS
2.
(a) a′) toward the left
d′) toward top of page
b′) into the page
c′) out of the page
e′) into the page
f′) out of the page
(b) The answer for each subpart is opposite to that given in part (a) above.
4.
(a) toward top of page
(b) out of page (
)
(c) zero force
(d) into the page
6.
8.
in the negative y-direction
(a)
(b) 0
10.
807 N
12.
(a) toward the left
(b) into the page
(c) out of the page
(d) toward top of page
(e) into the page
(f) out of the page
14.
(a) 0.12 N
(b) Both the direction of the field and the direction of the current must be known before the
direction of the force can be determined.
16.
eastward
18.
20.
(a)
at 15° above the horizontal in the northward direction
(b)
horizontal and due west
(a) 0.109 A
(b) toward the right
22.
24.
5.8 N into the page
26.
28.
9.98 N · m, clockwise about the
when viewed from above
30.
118 N · m
32.
(a) +x-direction, zero torque about x-axis
(b) –x-direction, zero torque about x-axis
(c) No. The two forces are equal in magnitude and opposite in direction, canceling each other,
and can have no effect on the motion of the loop.
(d) in the yz-plane at 130° counterclockwise from
. Torque is counterclockwise
about x-axis.
(e) counterclockwise about x-axis
(f)
(g) 130°
34.
(a)
(b)
36.
0.150 mm
(h) 0.155 N·m
38.
3.11 cm
40.
(a)
(b)
42.
(a)
(b)
44.
(a) toward the left
(b) out of the page
(c) lower left to upper right
46.
675 A downward
48.
(a) 40.0µT into the page
(b) 5.00µT out of the page
(c) 1.67µT out of the page
50.
(a)
toward the bottom of the page
(b)
52.
upward at 77.0° to the left of vertical
(a) in the –y-direction
(b) upward, in the positive z-direction
(c) The magnitude of the upward magnetic force must equal that of the downward gravitational
force.
54.
(d)
(e) 5.40 cm
(a)
(b)
(c)
This is as expected since the two field contributions have equal magnitudes and
opposite directions at the point midway between the wires.
56.
(a) 8.0 A
(b) opposite directions
(c) Reversing the direction of one current changes the force from repulsion to attraction.
Doubling the magnitude of one current doubles the magnitude of the force.
58.
60.
62.
207 W
64.
(a)
directed out of the page
(b) The forces on the two sides of the loop are equal in magnitude and opposite in direction,
canceling each other, and do not affect the state of balance of the system.
(c)
66.
(a) 5.00 cm
(b)
70.
(a)
(b) 0.40 s
72.
(a) opposite directions
(b) 68 A
74.
0.59 T
76.
(a)
(b)
(c)
(d)
68.