Slide 1 / 25
1
The induced current in the closed loop is largest
in which one of these diagrams?
A
Slide 2 / 25
2
B
A loop of wire is placed in a uniform magnetic
field directed into the page as shown above. The
magnitude of the magnetic field increases at a
constant rate. What is the direction of the induced
current in the loop?
A clockwise
B counter clockwise
D
C
C clockwise then counter clockwise
D counter clockwise then clockwise
E no current in the loop
E
Slide 3 / 25
3
A loop of wire is placed in a uniform magnetic
field directed out of the page as shown above.
The magnitude of the magnetic field decreases at
a constant rate. What is the direction of the
induced current in the loop?
Slide 4 / 25
4 A square loop of wire is moved at a constant
velocity v through a uniform magnetic field B
directed into the page. What is the direction of the
induced current in the loop as it passes through
the magnetic field?
A clockwise
Entering the field
B counter clockwise
C clockwise then counter clockwise
D counter clockwise then clockwise
A clockwise
clockwise
B counter clockwise
counter clockwise
C clockwise
E no current in the loop
counter clockwise
D counter clockwise
E
zero
Slide 5 / 25
5
Leaving the field
A square loop of wire is moved at a constant
velocity v through a uniform magnetic field B
directed into the page. What is the direction of the
induced magnetic force on the loop as it passes
through the magnetic field?
clockwise
zero
Slide 6 / 25
6
A small ring of wire is placed inside a large loop
connected to a battery and a switch. What is the
direction of the induced current in the ring just
after the switch is closed?
A clockwise
Entering the field
Leaving the field
A left
right
B right
C right
left
right
D left
left
E zero
zero
B counter clockwise
C clockwise then counter clockwise
D counter clockwise then clockwise
E no induced current
Slide 7 / 25
7
A conducting rod is pulled to the right at a
constant velocity v through a uniform magnetic
field B directed into the page. The rod rides on
two parallel conducting rails. What is the direction
of the induced current in the circuit?
Slide 8 / 25
8
A clockwise
A conducting rod of length L is pulled to the right
at a constant velocity v through a uniform
magnetic field B. The rod rides two conducting
rails connected to a resistor R. What is the
induced current in the circuit? Ignore the
resistance of the rod and the rails.
A
B counter clockwise
B
C clockwise then counter clockwise
C
D counter clockwise then clockwise
E no induced current
D
E
Slide 9 / 25
9
A conducting rod of length L is pulled to the right
at a constant velocity v through a uniform
magnetic field B. The rod rides two metallic rails
connected to a resistor R. What is the rate of
energy dissipation in the circuit? Ignore the
resistance of the rod and the rails.
Slide 10 / 25
10
A circular loop of wire is placed in the same plane
as a long wire carrying a steady current I. Which
of the following actions will not induce the current
in the loop?
A increasing current in the wire
A
B decreasing current in the wire
B
C moving the away from the wire
D moving the loop in parallel to the wire
C
E rotating the loop with respect to its diameter
D
E
Slide 11 / 25
11
A bar magnet with the north pole facing down is
dropped above a conducting ring. As the magnet
passes through the ring, what is the direction of
the induced current in the ring?
Slide 12 / 25
12
A bar magnet with the north pole facing down is
dropped above a conducting ring. Which one of
the following is true about the magnet’s
acceleration as it passes through the ring?
A always clockwise
A less than g
B always counter clockwise
B greater that g
C first clockwise then counter clockwise
C equals g
D first counter clockwise then clockwise
D twice g
E no induced current in the ring
E zero
Slide 13 / 25
13
Slide 14 / 25
14
A conducting rod moves to the right at a constant
velocity. The rod crosses a uniform magnetic field
directed out of the page. Which of the following
choices correctly describes the electric polarity of
the rod as it moves through the field?
A square loop of wire with a side s and resistance
R is placed in a uniform magnetic field of
magnitude B directed into the page. The field
begins to increase according to the formula B = β
+γt, where β and γ are positive constants. What is
the direction and magnitude of the induced
current I in the loop?
A
Top End
Bottom End
A positive
positive
B negative
negative
C positive
negative
D negative
positive
E zero
B
C
D
zero
E
Slide 15 / 25
15
Slide 16 / 25
16
A circular loop of wire with radius a is placed in a
uniform magnetic field perpendicular to the plane
of the loop. The magnetic field varies with time
generating an emf Ɛ = βπa2t1/2, where β is a
constant. What is the rate of change
of the magnetic field?
A circular loop of wire with radius a is placed in a
uniform magnetic field perpendicular to the plane
of the loop. The magnetic field varies with time
generating an emf Ɛ = βπa2t1/2, where β is a
constant. Assuming B (t=0) = 0,
which of the following formulas represents the
magnetic field as a function of time?
A
A
B
B
C
C
D
D
E
E
Slide 17 / 25
17
Slide 18 / 25
18
A rectangular loop of wire with dimensions a and
b moves with a constant speed v across a uniform
magnetic field B directed out of the page. Which
of the following graphs represents the induced
current in the loop as a function of the position x
of the leading edge of the loop?
A conducting rod moves to the right at a constant
velocity. The rod crosses a uniform magnetic field
directed out of the page. Which of the following
graphs represents the induced voltage between
the ends of the rod as a function of time?
A
C
B
A
C
D
B
E
D
E
Slide 19 / 25
19
Which of the following equations states: “A
changing magnetic field induces an electric
field?”
Slide 20 / 25
20
A
The magnetic field B at all points within the
shaded circle has an initial magnitude B. The
magnetic field is directed into the page and
begins decreasing at a constant rate. What is the
shape and direction of the electric field lines
induced in the circular space?
B
A parallel lines directed to the right
C
B parallel lines directed to the left
C concentric circles in the clockwise direction
D
D
concentric circles in the counter clockwise direction
E parallel lines directed into the page
E
Slide 21 / 25
21
A circular loop of wire with an area of 6×10 -3 m2
is placed in a uniform magnetic field
perpendicular to the plane of the loop. The
magnetic field decreases at a constant rate from
0.04 T to zero in 12 µs. What is the induced emf in
the loop?
Slide 22 / 25
22
A circular loop of wire with an area of 4.0×10 -3 m2
is placed in a uniform magnetic field
perpendicular to the plane of the loop. The
magnetic field increases at a constant rate from
zero to 0.050 T in 10.0 µs. If the electrical
resistance of the loop is 400.0 Ω, what is the rate
at which energy is dissipated in the loop as the
field increases?
A 10 V
B 20 V
A 0.4 W
C 40 V
B 1.6 W
D 60 V
C 3.2 W
E 80 V
D 1.2 W
E 1.0 W
Slide 23 / 25
23
A conducting ring with radius r = 0.10 m is placed
in a region of a spatially uniform magnetic field
perpendicular to the plane of the ring. The
magnetic field is directed into the page and is
decreasing at a rate of 0.050 T/s. What is the
magnitude of the induced electric field in the
ring?
Slide 24 / 25
24
A conducting ring with a radius r = 0.10 m is
placed in a region of a spatially uniform magnetic
field perpendicular to the plane of the ring. The
magnetic field is directed into the page and is
decreasing at the rate 0.050 T/s. What is the
magnitude of the induced current in the ring if its
resistance is 5.0 Ω?
A
5×10-3 V/m
A
5π×10-3 A
B
2.5×10 -3 V/m
B
2.5π×10-3 A
C
1.5×10 -4 V/m
C
π ×10-4 A
D
1×10-5 V/m
D
π×10-5 A
E
2×10-2 V/m
E
2π×10-2 A
Slide 25 / 25
25
An electric circuit consists of a charged capacitor
C, a resistor R and a switch S. Initially, the
switch is open and all devices are connected in
series. A circular loop of wire is placed in the
same plane as the circuit. Which one of the
following is true about the induced current in the
loop after the switch is closed?
A it is clockwise and increases
B it is counter clockwise and increases
C it is clockwise and decreases
D it is counter clockwise and decreases
E it is clockwise and constant