tovar (jdt436) – homework 32 – Turner – (59070)
1
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printout
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have
10
questions.
Multiplechoice questions may continue on
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before answering.
001
(part 1 of 3) 10.0 points
In an
LR
circuit, a 94 V(
rms
), 91 Hz source
is in series with a 21 mH inductor and a 22 Ω
resistor.
What is the maximum
rms
current?
Correct answer: 3
.
75049 A.
Explanation:
Let :
f
= 91 Hz
,
L
= 0
.
021 H
,
R
= 22 Ω
,
and
V
rms
= 94 V
.
The inductive reactance is
X
L
=
ω L
= 2
π f L
= 2
π
(91 Hz) (0
.
021 H)
= 12
.
0072 Ω
.
The impedance of an
RL
circuit is the same
as that of an
RLC
circuit, but without the
capacitive reactance. Namely
Z
=
radicalBig
R
2
+
X
2
L
=
radicalBig
(22 Ω)
2
+ (12
.
0072 Ω)
2
= 25
.
0634 Ω
.
The
rms
current is
I
rms
=
V
rms
Z
=
94 V
25
.
0634 Ω
=
3
.
75049 A
.
002
(part 2 of 3) 10.0 points
What is the power factor?
Correct answer: 0
.
877775.
Explanation:
The phase angle in an
RL
circuit is the
same as that of an
RLC
circuit, but without
the capacitive reactance. Namely
φ
= tan
−
1
parenleftbigg
X
L
R
parenrightbigg
= tan
−
1
parenleftbigg
12
.
0072 Ω
22 Ω
parenrightbigg
= 28
.
6249
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 Spring '08
 Turner
 Inductance, Work, RLC, Correct Answer, Inductor, RL circuit

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