EECS 211 Circuits I
Spring Semester 2014
Assignment #9 Due 1 April 2014
Reading: Sections 5.3 - 5.6, 6.1, 6.2 in Irwin/Nelms;
Learning Assessments: All in Reading assignment (do not hand in)
Problems
1.
The class demonstration this week used the circuit below. This problem repeats that
demonstration, except that you will calculate values rather than measuring them as we did in the
demonstration. The answers are not in the back of the book, but if you were paying attention
during the demo, you should already know what the answers should be (approximately)!
X
20 kΩ
20 kΩ
15 kΩ
6V
RL
9V
20 kΩ
10 kΩ
Y
a.
Calculate the open-circuit voltage v oc at terminals X and Y with load resistor R L removed.
b.
Find the short-circuit current i sc at terminals X and Y with load resistor R L shorted.
c.
Find the Thevenin resistance RTh of the network seen by resistor R L using v oc and i sc .
d.
Find the Thevenin resistance of the network seen by resistor R L by finding the equivalent
resistance of the "dead" network.
e.
Use the Thevenin equivalent to calculate the value V L when R L is 10 kΩ.
f.
Verify that the load resistor absorbs more power when its value is 10 kΩ than if its value is
9 kΩ or 11 kΩ.
2.
Work problem 3.78 (p. 150) using Thevenin’s theorem in the following particular way. Break the
circuit into two pieces by cutting vertically between the 4 kΩ resistor and the 12 V source. Then
find the Thevenin equivalent of the left portion of the circuit (note that it contains a dependent
source, but no independent sources). Then re-attach the Thevenin equivalent to the right portion
of the circuit, and find V o .
3.
Use the circuit of Figure 3PFE-4 (page 155) for this problem. There is a node voltage V x shown,
but its reference node has been omitted -- the reference node should be the bottom node. Break
this circuit just to the left of the 2Ω resistor (at both the top and bottom), then consider everything
Prof. Petr
Copyright 2014 David W. Petr
Spring 2014
EECS 211
-2-
Assignment #9
to the left of the break to be Network B and everything to the right of the break (including the 2Ω
resistor) to be Network A. Find the Thevenin equivalent of Network A (which contains a
dependent source but no independent sources), and then use that Thevenin equivalent to find the
value of V x .
4.
This Capture/PSpice problem will count as much as two regular problems. We will be able to
determine easily if you have simply copied someone else’s schematic and/or output file.
Use Capture/PSpice to simulate the circuit from problem 10 in assignment 5. Place the ground as
follows. If your 7-digit KUID ends in 0 or 1, place the ground at the node connecting the 120 V
sources. If your 7-digit KUID ends in 2 or 3, place the ground at the upper left node in the figure.
If your 7-digit KUID ends in 4 or 5, at the upper right node. If your 7-digit KUID ends in 6 or 7,
at the lower right node. If your 7-digit KUID ends in 8 or 9, at the lower left node. Label all other
nodes with numbers. Turn in the following:
a.
A printout of your circuit schematic as it existed after you ran the PSpice simulation.
Note: the node voltages should be displayed on the schematic.
b.
A printout of the PSpice output (text) file, with the total power dissipation circled and a
notation showing that this matches the total power dissipation given in the solutions to
assignment 6 (problem 1, part c).
c.
Calculations (by hand, either on the schematic printout or the output file printout) showing
that the values for V a , V b and V c obtained from PSpice match the values in the solutions to
assignment 6 (problem 1, part a).
5.
Problem 6.4, p. 281. Capacitor charge, voltage relationship.
6.
Problem 6.17, p. 282. Capacitor current from voltage.
7.
Problem 6.18, p. 282. Capacitor current from voltage.
8.
Problem 6.20, p. 283. Capacitor voltage from current.
9.
Suppose you have a circuit with two terminals (nodes) X and Y. Suppose also that you require 40
pF of capacitance between X and Y, but you only have 30 pF capacitors available. Show how you
could arrange the 30 pF capacitors to obtain the desired 40 pF capacitance.
Prof. Petr
Copyright 2014 David W. Petr
Spring 2014