hopkins (tlh982) – HW08 – criss – (4908)
1
This
printout
should
have
11
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
001
(part 1 of 4) 10.0 points
The primary coil of a certain transformer has
an inductance of 1
.
16 H and a resistance of
71
.
7 Ω.
If the primary coil is connected to an ac
source with a frequency of 93
.
4 Hz and a
voltage of 150 V
rms
, what is the
rms
current
through the primary?
Correct answer: 0
.
219135 A.
Explanation:
Let :
f
= 93
.
4 Hz
,
L
= 1
.
16 H
,
R
= 71
.
7 Ω
,
and
V
rms
= 150 V
.
X
L
= 2
π f L
= 2
π
(93
.
4 Hz)(1
.
16 H)
= 680
.
745 Ω
,
and
Z
=
radicalBig
X
2
L
+
R
2
=
radicalBig
(680
.
745 Ω)
2
+ (71
.
7 Ω)
2
= 684
.
511 Ω
.
So the
rms
current is
I
rms
=
V
rms
Z
=
150 V
684
.
511 Ω
=
0
.
219135 A
.
002
(part 2 of 4) 10.0 points
If the primary is connected to 72
.
4 V dc, what
is the current through the primary? Disregard
initial effects.
Correct answer: 1
.
00976 A.
Explanation:
I
=
V
R
=
72
.
4 V
71
.
7 Ω
=
1
.
00976 A
.
003
(part 3 of 4) 10.0 points
In case 1, find the power dissipated in the
resistance.
Correct answer: 3
.
44303 W.
Explanation:
In case 1,
P
=
I
2
rms
R
= (0
.
219135 A)
2
(71
.
7 Ω)
=
3
.
44303 W
.
004
(part 4 of 4) 10.0 points
In case 2, find the power dissipated in the
resistance.
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 Fall '08
 RobertR.Criss
 Physics, Alternating Current, Correct Answer

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