1
FINAL EXAM
Physics 108
Fall 2003
December 17, 2003
3:30 p.m.  6:30 p.m.
Print your FIRST name: ________________________________
Print your LAST name: ________________________________
Sign your name: ______________________________________
Person number: ______________________________________
Circle your lecture Instructor
Cerne
T,Th 12:301:45 pm
Petrou
M,W,F 2:002:50 pm
Instructions
•
This is a closed book exam
•
There are four problems
•
Allow approximately 30 minutes for each problem (P) and 15 minutes for each mini
problem (MP)
•
You must show ALL work to receive full credit.
•
Numerical answers must have the right units, and if vectors proper directions
•
Use the back of the problem page if you need more space and mark OVER
→
on the
front of the page so that your work will be counted.
•
Place your answers in the answer boxes at the bottom of each problem page.
Useful Constants
ε
o
= 8.85
×
10
12
C
2
/N.m
2
k = 8.99
×
10
9
Nm
2
/C
2
e = 1.6
×
10
19
C
m
e
= 9.11
×
10
31
kg
µ
o
= 4
π×
10
7
T.m/A
m
p
= 1.67
×
10
27
kg
Please do not write below this line
Problem Number
Maximum Score
Your Score
Grader
P1
25
P2
25
P3
25
MP1
15
MP2
15
MP3
15
MP4
15
MP5
15
MP6
15
TOTAL
165
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____________________________
P1.
A rectangular wire loop (dimensions: h = 12.0 cm,
w = 15.0 cm) is placed in a
uniform magnetic field
B
as shown in fig.a.
The magnetic field B changes with time t as
shown in fig.b.
The resistance R of the loop is 0.5
Ω
a.
(6)
Determine the induced emf
E
on the loop for 0 < t < 0.1 s
b.
(6)
Determine the induced emf
E
' on the loop for 0.1 s
< t < 0.2 s
c.
(2) Calulate the induced current I during the time interval 0 < t < 0.1 s
d.
(6)
Use Lenz’s rule to determine the direction of the induced current during the time
interval
0 < t < 0.1 s
e.
(5) Determine the total charge Q that flows through a cross section of the loop wire
during the time interval 0 < t < 0.2 s
C
10
4
.
5
1
.
0
0
1
.
0
10
4
.
5
It
Q
(e)
flux
magnetic
the
reduce
to
tends
thus
and
B
of
direction
opposite
in the
is
B
field
magnetic
induced
that the
so
fig.a)
(see
direction
(CW)
clockwise
in the
flow
must
current
induced
The
increases.
flux
magnetic
the
(a)
part
From
)
(
10
4
.
5
5
.
0
10
7
.
2
R
I
)
(
0
0
)
15
.
0
(
)
12
.
0
(
dt
d
)
(
10
7
.
2
1
.
0
0
15
.
0
)
15
.
0
(
)
12
.
0
(
dt
d
dt
d
)
(
3
2
ind
2
2
2
−
−
−
−
−
×
=
×
+
×
×
=
=
Φ
×
=
×
−
=
=
=
×
×
−
=
−
=
′
×
−
=
−
×
−
=
−
=
Φ
−
=
→
=
Φ
d
A
c
B
hw
b
V
B
hw
Bhw
a
E
E
E
E
Place your answers here.
(a)
E
=
V
2
10
7
.
2
−
×
−
(6)
(b)
E
′
= 0
(6)
(c)
I =
A
2
10
4
.
5
−
×
(3)
(d)
Direction of I:
Circle one:
CW
CCW
(6)
(
e
)
Q
=
C
10
4
.
5
3
−
×
(5)
B
0.15 T
O
0.1 s
0.2 s
t
Fig.b
h
w
B
Fig.a
X
.
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 Spring '08
 Halstead
 Physics, Magnetic Field, RLC, Lenz, BHW, Qnet, Instructor Cerne Petrou

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