260
Inductance
P32.75
(a)
It has a magnetic field, and it stores energy, so
L
U
I
=
2
2
is non-zero.
(b)
Every field line goes through the rectangle between the conductors.
(c)
Φ =
LI
so
L
I
I
BdA
y
a
w
a
=
=
=
−
z
Φ
1
L
I
xdy
I
y
I
w
y
I
Ix
y
dy
x
y
a
w
a
a
w
a
=
+
−
F
H
G
I
K
J
=
=
−
−
z
z
1
2
2
2
2
2
2
0
0
0
0
µ
π
µ
π
µ
π
µ
π
b
g
ln
.
Thus
L
x
w
a
a
=
−
F
H
G
I
K
J
µ
π
0
ln
.
P32.76
For an
RL
circuit,
I t
I
e
R L t
a f
b
g
=
−
max
:
I t
I
e
R
L
t
R L t
a f
b
g
max
=
−
=
≅
−
−
−
1
10
1
9
R
L
t
=
−
10
9
so
R
max
.
.
.
.
=
×
×
=
×
−
−
−
3 14
10
10
2 50
3 16
10
3 97
10
8
9
7
25
e
je
j
b
g
e
j
yr
s yr
Ω
.
(If the ring were of purest copper, of diameter 1 cm, and cross-sectional area
1 mm
2
, its resistance
would be at least
10
6
−
Ω
).
P32.77
(a)
U
LI
B
=
=
×
=
×
1
2
1
2
50 0
50 0
10
6 25
10
2
3
2
10
.
.
.
H
A
J
a
f
e
j
(b)
Two adjacent turns are parallel wires carrying current in the same direction. Since the loops
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- Fall '11
- Staff
- Physics, Inductance, Energy, Magnetic Field, Inductor, RL circuit, Field line, yg JK
-
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