Current vs. Voltage (I-V) Characteristic Notes | EduRev

: Current vs. Voltage (I-V) Characteristic Notes | EduRev

 Page 1


1
Lecture 4, Slide 1 EECS40, Fall 2003 Prof. King
Announcements
• Visit the class website to see updated TA 
section assignments
http://www-inst.eecs.berkeley.edu/~ee40
• Lab section 13 (Mondays 6-9PM) is cancelled
• Prof. King’s Office Hour tomorrow (Thu. 9/4) 
will be held from 8:30AM-9:30AM
• HW assignments will NOT be accepted in 
class.  Turn in your assignments BEFORE 
class on Friday in 240 Cory.
Lecture 4, Slide 2 EECS40, Fall 2003 Prof. King
Lecture #4
OUTLINE
• Circuit element I-V characteristics
• Construction of a circuit model 
• Kirchhoff’s laws – a closer look
Reading
(Finish Chapter 2)
Page 2


1
Lecture 4, Slide 1 EECS40, Fall 2003 Prof. King
Announcements
• Visit the class website to see updated TA 
section assignments
http://www-inst.eecs.berkeley.edu/~ee40
• Lab section 13 (Mondays 6-9PM) is cancelled
• Prof. King’s Office Hour tomorrow (Thu. 9/4) 
will be held from 8:30AM-9:30AM
• HW assignments will NOT be accepted in 
class.  Turn in your assignments BEFORE 
class on Friday in 240 Cory.
Lecture 4, Slide 2 EECS40, Fall 2003 Prof. King
Lecture #4
OUTLINE
• Circuit element I-V characteristics
• Construction of a circuit model 
• Kirchhoff’s laws – a closer look
Reading
(Finish Chapter 2)
2
Lecture 4, Slide 3 EECS40, Fall 2003 Prof. King
Current vs. Voltage (I-V) Characteristic
• Voltage sources, current sources, and 
resistors can be described by plotting the 
current (i) as a function of the voltage (v)
• Later, we will see that the I-V characteristic of 
any circuit consisting only of sources and 
resistors is a straight line.
+
v
_
i
Lecture 4, Slide 4 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Voltage Source
1. Plot the I-V characteristic for v
s
> 0.  For what 
values of i does the source absorb power?  For 
what values of i does the source release power?
2. Repeat (1) for v
s
< 0.
3. What is the I-V characteristic for an ideal wire?
+
_
v
s
i
i
+
v
_
v
Page 3


1
Lecture 4, Slide 1 EECS40, Fall 2003 Prof. King
Announcements
• Visit the class website to see updated TA 
section assignments
http://www-inst.eecs.berkeley.edu/~ee40
• Lab section 13 (Mondays 6-9PM) is cancelled
• Prof. King’s Office Hour tomorrow (Thu. 9/4) 
will be held from 8:30AM-9:30AM
• HW assignments will NOT be accepted in 
class.  Turn in your assignments BEFORE 
class on Friday in 240 Cory.
Lecture 4, Slide 2 EECS40, Fall 2003 Prof. King
Lecture #4
OUTLINE
• Circuit element I-V characteristics
• Construction of a circuit model 
• Kirchhoff’s laws – a closer look
Reading
(Finish Chapter 2)
2
Lecture 4, Slide 3 EECS40, Fall 2003 Prof. King
Current vs. Voltage (I-V) Characteristic
• Voltage sources, current sources, and 
resistors can be described by plotting the 
current (i) as a function of the voltage (v)
• Later, we will see that the I-V characteristic of 
any circuit consisting only of sources and 
resistors is a straight line.
+
v
_
i
Lecture 4, Slide 4 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Voltage Source
1. Plot the I-V characteristic for v
s
> 0.  For what 
values of i does the source absorb power?  For 
what values of i does the source release power?
2. Repeat (1) for v
s
< 0.
3. What is the I-V characteristic for an ideal wire?
+
_
v
s
i
i
+
v
_
v
3
Lecture 4, Slide 5 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Current Source
1. Plot the I-V characteristic for i
s
> 0.  For what values 
of v does the source absorb power?  For what 
values of v does the source release power?
2. Repeat (1) for i
s
< 0.
3. What is the I-V characteristic for an open circuit?
i
i
+
v
_
v
i
s
Lecture 4, Slide 6 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Resistor
1. Plot the I-V characteristic for R = 1 k? .  What is the 
slope?
i
i
+
v
_
v
R
Page 4


1
Lecture 4, Slide 1 EECS40, Fall 2003 Prof. King
Announcements
• Visit the class website to see updated TA 
section assignments
http://www-inst.eecs.berkeley.edu/~ee40
• Lab section 13 (Mondays 6-9PM) is cancelled
• Prof. King’s Office Hour tomorrow (Thu. 9/4) 
will be held from 8:30AM-9:30AM
• HW assignments will NOT be accepted in 
class.  Turn in your assignments BEFORE 
class on Friday in 240 Cory.
Lecture 4, Slide 2 EECS40, Fall 2003 Prof. King
Lecture #4
OUTLINE
• Circuit element I-V characteristics
• Construction of a circuit model 
• Kirchhoff’s laws – a closer look
Reading
(Finish Chapter 2)
2
Lecture 4, Slide 3 EECS40, Fall 2003 Prof. King
Current vs. Voltage (I-V) Characteristic
• Voltage sources, current sources, and 
resistors can be described by plotting the 
current (i) as a function of the voltage (v)
• Later, we will see that the I-V characteristic of 
any circuit consisting only of sources and 
resistors is a straight line.
+
v
_
i
Lecture 4, Slide 4 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Voltage Source
1. Plot the I-V characteristic for v
s
> 0.  For what 
values of i does the source absorb power?  For 
what values of i does the source release power?
2. Repeat (1) for v
s
< 0.
3. What is the I-V characteristic for an ideal wire?
+
_
v
s
i
i
+
v
_
v
3
Lecture 4, Slide 5 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Current Source
1. Plot the I-V characteristic for i
s
> 0.  For what values 
of v does the source absorb power?  For what 
values of v does the source release power?
2. Repeat (1) for i
s
< 0.
3. What is the I-V characteristic for an open circuit?
i
i
+
v
_
v
i
s
Lecture 4, Slide 6 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Resistor
1. Plot the I-V characteristic for R = 1 k? .  What is the 
slope?
i
i
+
v
_
v
R
4
Lecture 4, Slide 7 EECS40, Fall 2003 Prof. King
“Lumped Element” Circuit Modeling
(Model = representation of a real system which simplifies analysis)
• In circuit analysis, important characteristics are 
grouped together in “lumps” (separate circuit 
elements) connected by perfect conductors (“wires”)
• An electrical system can be modeled by an electric 
circuit (combination of paths, each containing 1 or 
more circuit elements) if 
? = c/f >> physical dimensions of system
Distance travelled by a particle travelling at the speed of light
in one period
Example:  f = 60 Hz
? = 3 x 10
8
m/s / 60 = 5 x 10
6
m
Lecture 4, Slide 8 EECS40, Fall 2003 Prof. King
Construction of a Circuit Model
• The electrical behavior of each physical 
component is of primary interest.
• We need to account for undesired as well 
as desired electrical effects.
• Simplifying assumptions should be made 
wherever reasonable.
Page 5


1
Lecture 4, Slide 1 EECS40, Fall 2003 Prof. King
Announcements
• Visit the class website to see updated TA 
section assignments
http://www-inst.eecs.berkeley.edu/~ee40
• Lab section 13 (Mondays 6-9PM) is cancelled
• Prof. King’s Office Hour tomorrow (Thu. 9/4) 
will be held from 8:30AM-9:30AM
• HW assignments will NOT be accepted in 
class.  Turn in your assignments BEFORE 
class on Friday in 240 Cory.
Lecture 4, Slide 2 EECS40, Fall 2003 Prof. King
Lecture #4
OUTLINE
• Circuit element I-V characteristics
• Construction of a circuit model 
• Kirchhoff’s laws – a closer look
Reading
(Finish Chapter 2)
2
Lecture 4, Slide 3 EECS40, Fall 2003 Prof. King
Current vs. Voltage (I-V) Characteristic
• Voltage sources, current sources, and 
resistors can be described by plotting the 
current (i) as a function of the voltage (v)
• Later, we will see that the I-V characteristic of 
any circuit consisting only of sources and 
resistors is a straight line.
+
v
_
i
Lecture 4, Slide 4 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Voltage Source
1. Plot the I-V characteristic for v
s
> 0.  For what 
values of i does the source absorb power?  For 
what values of i does the source release power?
2. Repeat (1) for v
s
< 0.
3. What is the I-V characteristic for an ideal wire?
+
_
v
s
i
i
+
v
_
v
3
Lecture 4, Slide 5 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Current Source
1. Plot the I-V characteristic for i
s
> 0.  For what values 
of v does the source absorb power?  For what 
values of v does the source release power?
2. Repeat (1) for i
s
< 0.
3. What is the I-V characteristic for an open circuit?
i
i
+
v
_
v
i
s
Lecture 4, Slide 6 EECS40, Fall 2003 Prof. King
I-V Characteristic of Ideal Resistor
1. Plot the I-V characteristic for R = 1 k? .  What is the 
slope?
i
i
+
v
_
v
R
4
Lecture 4, Slide 7 EECS40, Fall 2003 Prof. King
“Lumped Element” Circuit Modeling
(Model = representation of a real system which simplifies analysis)
• In circuit analysis, important characteristics are 
grouped together in “lumps” (separate circuit 
elements) connected by perfect conductors (“wires”)
• An electrical system can be modeled by an electric 
circuit (combination of paths, each containing 1 or 
more circuit elements) if 
? = c/f >> physical dimensions of system
Distance travelled by a particle travelling at the speed of light
in one period
Example:  f = 60 Hz
? = 3 x 10
8
m/s / 60 = 5 x 10
6
m
Lecture 4, Slide 8 EECS40, Fall 2003 Prof. King
Construction of a Circuit Model
• The electrical behavior of each physical 
component is of primary interest.
• We need to account for undesired as well 
as desired electrical effects.
• Simplifying assumptions should be made 
wherever reasonable.
5
Lecture 4, Slide 9 EECS40, Fall 2003 Prof. King
Terminology: Nodes and Branches
Node: A point where two or more circuit elements 
are connected – entire wire
Branch: A path that connects two nodes
Lecture 4, Slide 10 EECS40, Fall 2003 Prof. King
Notation: Node and Branch Voltages
• Use one node as the reference (the “common” 
or “ground” node) – label it with a symbol
• The voltage drop from node x to the reference 
node is called the node voltage v
x
.
• The voltage across a circuit element is defined 
as the difference between the node voltages at 
its terminals
Example:
+
_
v
s
+
v
a
_
+
v
b
_
ab
c
R
1
R
2
–v
1  
+
Read More
Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!