17) If the circular conductor in the figure below undergoes
thermal expansion while it is in a uniform magnetic field, a
current will be induced clockwise around it. Is the magnetic
field directed into the page or out of it?
1) into the page
2) out of the page
18) A loop of wire is sitting in a uniform, constant magnet field
as shown. Suddenly, the loop is bent into a smaller area loop.
During the bending of the loop, the induced current in the loop
is
1) zero
2) clockwise
3) counterclockwise
19) What is the direction of the induced current in each of the
circular loops in the figure below?
1) (a) CW
2) (a) CW
3) (a) CCW
4) (a) CCW
(b) CW
(b) CCW
(b) CCW
(b) CW
20) The straight wire in the figure below carries a constant
current i. While the rectangular loop is being moved away from
the wire, the induced current in the loop is
1) zero
2) clockwise
3) counterclockwise
21) A loop of wire is brought near a long straight wire carrying a
current I. The direction of the current induced in the loop is
1) Clockwise
2) Counter-clockwise
3) zero
4) Not enough information to tell.
22) A long, straight wire is in the same plane as a wooden,
nonconducting loop. The wire carries an increasing current I in
the direction shown in the figure.
1) There will be no induced emf and no induced current.
2) There will be a counterclockwise induced emf, but no induced
current.
3) There will be a clockwise induced emf, but no induced
current.
4) There will be a clockwise induced current in the loop.
5) There will be a counterclockwise induced current in the loop.
23) In the figure shown, a loop of wire is near a long straight
current-carrying wire. Which way should the loop move to
induce a clockwise current?
1) up
2) down
3) left
4) right
24) A long, straight wire carrying an increasing current I passes
along a diameter of a wire loop. The straight wire and the loop
are in the same plane but are not in electrical contact. The
induced current in the loop is:
1) zero.
2) counter-clockwise
3) clockwise.
25) A rectangular loop of wire is placed midway between two
long straight parallel conductors as shown. The conductors carry
currents i1 and i2, as indicated. If i1 is increasing and i2 is
constant, then the induced current in the loop is:
.
1) zero
2) clockwise
3) counterclockwise
4) depends on i1 – i2
5) depends on i1 + i2
26) A loop of wire is near a long straight wire that is carrying a
large current I, which is decreasing. The loop and the straight
wire are in the same plane and are positioned as shown. The
current induced in the loop is
1) counter-clockwise
2) clockwise
3) zero
27) Two circuits are shown at right. When the switch is initially
closed, the current in loop B
1) runs clockwise.
2) runs counterclockwise.
3) There is no current
28) Two circuits are shown at right. When the switch has been
closed a long time, the current in loop B
1) runs clockwise.
2) runs counterclockwise.
3) There is no current.
29) If the variable resistance R in the left-hand circuit of the
figure below is increased at a steady rate, is the current induced
in the right-hand loop clockwise or counterclockwise?
1) clockwise
2) counterclockwise
30) A hand-cranked electric generator is rotating CCW in a
constant uniform B-field which points right, as shown. What can
you say about the current generated by the loop at this moment?
1) It's a maximum at the instant shown.
2) It's zero at the exact instant shown.
3) It's not zero, but is changing, at the instant shown.
31) Ring #1 has a steady current I1 through it as shown. What
happens in ring #2?
1) The current flows in direction A
2) The current flows in direction B
3) No current is induced in ring #2.
32) Ring #1 has a steadily increasing current I1 through it as
shown. What happens in ring #2?
1) The current flows in direction A
2) The current flows in direction B
3) No current is induced in ring #2.
33) A metal rod is placed across two metal rails that are
connected to a battery and a switch. When the switch is closed,
the rod
1) moves to the right.
2) moves to the left.
3) doesn't move.
34) A wire loop, moving right, enters a region where there is a
constant, uniform magnetic field pointing into the page.
As the loop enters the B-field, the current induced in the loop is
1) CW
2) CCW
35) A conducting bar moves to the left at a constant speed v on
two conducting rails joined at the left as shown. As a result of
the bar moving through a constant magnetic field, a current I is
induced in the indicated direction. Which one of the following
directions is that of the magnetic field?
1) toward the right
2) toward the left
3) parallel to the long axis of the bar
4) into the page
5) out of the page
36) Two conducting loops carry equal currents I in the same
direction as shown in the figure. If the current in the upper loop
suddenly drops to zero, what will happen to the current in the
bottom loop according to Lenz’s law?
1) The current will decrease.
2) The current will increase.
3) The current will not change.
4) The current will also drop to zero.
5) The current will reverse its direction.
37) A square metal loop moves at constant velocity v through a
region with a magnetic field directed into the page.
At which point(s) does the induced current in the loop flow
clockwise?
1) 2
2) 4
3) 3
4) both 2 and 4
38) A square loop of wire moves with a constant speed v from a
field-free region into a region of constant uniform magnetic
field, as shown.
Which of the five graphs correctly shows the induced current i
in the loop as a function of time t?
39) A copper penny slides on a horizontal frictionless table.
There is a square region of constant uniform magnetic field
perpendicular to the table, as shown.
Which graph correctly shows the speed v of the penny as a
function of time t?