Patel, Kinal – Homework 17 – Due: Apr 4 2008, 7:00 pm – Inst: Weathers
1
This
printout
should
have
10
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
The due time is Central
time.
001
(part 1 of 1) 10 points
A transformer has input voltage and current
of 12 V and 5 A respectively, and an output
current of 0
.
7 A.
If there are 1365 turns turns on the sec
ondary side of the transformer, how many
turns are on the primary side?
Correct answer: 191
.
1 turns.
Explanation:
Let :
n
s
= 1365 turns
,
I
p
= 5 A
,
and
I
s
= 0
.
7 A
.
Energy is conserved, so
P
p
=
P
s
I
p
V
p
=
I
s
V
s
V
p
V
s
=
I
s
I
s
For the transformer
V
∝
n
n
p
n
s
=
V
p
V
s
=
I
s
I
p
n
=
n
s
I
s
I
p
= (1365 turns)
0
.
7 A
5 A
=
191
.
1 turns
.
keywords:
002
(part 1 of 2) 10 points
A stepup transformer is connected to a gen
erator that is delivering 133 V and 110 A.
The ratio of the turns on the secondary to the
turns on the primary is 1040 to 5.
What voltage is across the secondary?
Correct answer: 27
.
664 kV.
Explanation:
Let :
n
s
n
p
=
1040
5
= 1040
and
V
p
= 133 V
.
V
∝
n
so
V
s
V
p
=
n
s
n
p
The stepped up voltage in secondary is
V
s
=
V
p
·
n
s
n
p
= (133 V) (1040)
·
1 kV
1000 V
=
27
.
664 kV
.
003
(part 2 of 2) 10 points
What current flows in the secondary?
Correct answer: 528
.
846 mA.
Explanation:
Let :
I
p
= 110 A
.
Energy is conserved, so
P
p
=
P
s
I
s
V
s
=
I
p
V
p
I
s
=
I
p
V
p
V
s
=
(110 A) (133 V)
27664 V
·
10
3
mA
1 A
=
528
.
846 mA
.
keywords:
004
(part 1 of 1) 10 points
Consider an audio amplifier with an output
impedance of 663 Ω and a speaker that has an
input impedance of 36 Ω. A circuit replicating
this is shown in the figure below.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 Weathers
 Energy, Work, Alternating Current, Speed of light, Correct Answer, Input impedance, Impedance matching

Click to edit the document details