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Lectures
Lecture: 23 (iq21)
Microscopic picture of a circuit
1. A simple circuit: Macro vs
micro descriptions
2. Drude model and drift velocity
3. Gradual surface charge leading to constant E.
4. Steady state of a current flow in a circuit
a. One loop: i maintains the
same value throughout
b. Node: iin=i1+i2
5. Examples
a. Loop equations and node equations Kirchhoff’s laws.
b. Simple circuit
c. Example with a simple series connection
d. Example with a simple parallel connection
e. Example with 4 identical bulbs
Announcement:
Midterm 2: Class average
is 76.
o
How to determine
the letter grade you made for this midterm?
o
Find you scaled
score which is located near the bottom of the grading page.
o
Two letter grades
for each exam:
§ letter grade-1 based on % cutoffs.
§ Letter grade-2 based on scaled score cutoffs.
o
The letter grade you have made for this exam
is the higher of the two letter grades, if there is a difference.
o
I congratulate
those of you who have done well in this exam.
o
Those have done
below 60, you
need to look for ways to improve your performance.
o
I encourage you
to work all the problems you have missed without looking at the solutions.
o
Come to talk to me
during my office hours, or other time by appointment. Bring your work with you when you come.
o
Ch19.h1:
o
004 Choose all
correct answers
o
008 Assume the
time required to reach the steady state is with the speed of light.
o
018 Of the
following diagrams, which indicates qualitatively
correct surface charge distribution …