Transcript Document 7367198

ENTC 4350
HOMEWORK SET 4
Chapter 6
Chapter 6, Problem 1.

A copper wire, 45 cm long, has a crosssectional area of 0.05 cm2. Calculate its
resistance. (Hint: The resistivitiy of
copper is 17 x 10-8 W.
1m 

 45 cm 

L
100cm 

8
R    1.7  10 W  m
2
A


1
m
2
 0.05 cm 

2




100
cm


Chapter 6, Problem 1.
0.45 m
R  1.7  10 W  m
 0.00153 W
6
2
5  10 m
8
Chapter 6, Problem 3.

In the Wheatstone bridge shown in
Figure 6-24, assume that R1 = 1.5 kW,
R2 = 780 W, R3 = 990 W, and R4 = 1.2
kW. Find the output voltage when an
excitation voltage of +5 V dc is applied.
 R2
R4 

Eo   E 

 R1  R2 R3  R4 
Chapter 6, Problem 3.


780 W
1200 W

 5V 

 1500 W  780 W 990 W  1200 W 
 5V 0.342  0.548   1.03 V
Chapter 6, Problem 4.

A blood pressure transducer is based on
the Wheatstone bridge. The sensitivity
is nominaly rated at 50 mV/(V*mm Hg).
Find the output voltage if an excitation
potential of +7.5 V and a pressure of 100
torr is applied. [Note 1 torr = 1 mm Hg.]
Eo  EF
Chapter 6, Problem 4.
50 mV
Eo 
 7.5 V  100
V  mm Hg
 37500 mV  0.0375 V
Chapter 6, Problem 5.

A 40-mm length wire has a resistance of
100 W. When a tension is applied, the
resistance changes to 80 W and the
length becomes 40.04 mm. Calculate
the gauge factor.
R
G.F . 
10080 W
R
100W
 40.04 40 mm
L
40 mm
L
20 / 100 0.2


5
0.04
0.04
Chapter 6, Problem 6.
Eo  EF
Chapter 6, Problem 6.
50 mV
Eo 
 7.5V  120 g
V g
 45000 mV  0.045V
Chapter 6, Problem 9.
0.55
0.55  4
C

  R    0.15 
ln  r  ln  0.1 

    
2.2
2.2


 5.43 pF
ln 1.5 0.405