chapter 1 linear circuit analysis

8/11/2019 Chapter 1 Linear Circuit Analysis

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Quiz on most Mondays (basically one of the previous homework problems)

Homework due by 11:30 am on the assigned date.Submitted online at www.kohne.net

Answers are available online after 11:30

Homework(12) 35% due most Mondays

Quizzes (10) 20% most Mondays - Each quiz will be a homework question

Exams (3) 30%

Final Exam 15%

More than 3 absences will cause reduction of grade by 0.33 (An A- becomes a B+)

More than 5 absences will cause reduction of grade by 1.0 (An A becomes a B)

While there is a lot of graded work, this is advantageous to you. Each deliverable isrelatively simple, and therefore easy for you to produce. Also, if you mess-up on one, itdoesnt hurt you very much.

Do a little homework after each class. 55% of your grade is homework + quizzes

Doing it all on the weekend will ruin your weekend !!!!!!!
http://www.kohne.net/http://www.kohne.net/


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Chapter 1

The McNuggets

SI units

The words Volts

Amps

Coulombs

Joules

Watts

Labeling conventions (signs/polarity)

Supplying/Absorbing

Passive/Active

Potential energy/ Kinetic energy

All problems are solved with easy to remember PROCEDURES

Learn the definitions

See the symbols

Chargethe electron

6.28 * 10 18 electrons = 1 Coulomb

Positive-negative charge carriers

Currentflow of positive charge carriers

Ampere (Amp) = 1 C/s


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How big or small are various currents?

Voltageraises energy of the charge

electromotive force (EMF)

Always between two points(no absolute zero)

Battery (via chemical reaction)

pumps up PE of charges


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Sometimes the value of a voltage difference is unknown,Assign a reference polarity and value, V

If we measure the voltage between thenodes and find it to be 2 volts as shown

Then V = 2 V

If the measurement reveals that,in reality, the voltage between thenodes is as shown below,

Then V = -5 V

The two index notation for voltages

Since voltages are always differences,

the 2 V below is V A VB

OR VAB = 2 V

If asked for V BA

What would be the answer?

What is V BA ?

What is V AB ?


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Symbols - Active components

Not time varying

Time varying (independent)

Time varying (dependent)

Symbols - Passive components Passive sign convention

Supplies Absorbs


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When solving for unknown parameters,always start with what you know.

We know that the resistors are passive,so give them appropriate labels

If V R1 8 volts and the power absorbed by it is12 W then the current thru it must be 1.5 A

Now we also know the value of V R2VR2 = -6 V

If the power absorbed by R 2 is 12 W,then the current must be:

I = (12W)/(-6V) = -2 A

Its now evident that we assigned I x wrong, so correct it.

We also know the magnitude of I x so put it in

Power supplied:

24V battery

#1

36 W

8 W

Power absorbed:

R1

R2

10V battery

12 W

12 W

20 W

44 W 44 W


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Drill Example 1: No new material here

Since the resistors are passive components, and youknow the direction of current thru them, label thevoltages correctly

We are told the voltages across theresistors, so put them in

Now you know the voltages across thecurrent sources and the current thru thevoltage source

Find the power supplied or absorbed by each source in the circuitbelow.

P6V = _____ ? Supplied or Absorbed

P1A = _____ ? Supplied or AbsorbedP2A = _____ ? Supplied or Absorbed

The answers should now be obvious.

Drill Example 2

Find the power supplied or absorbed by each source in the circuitbelow.

P6V = _____ ? Supplied or AbsorbedP1A = _____ ? Supplied or AbsorbedP2A = _____ ? Supplied or Absorbed

Put down what you can see from inspection

We are told the voltages across theresistors, so put them in


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Revisit ideas in more detail

q is the amount of charge (in Coulombs). It can vary over time; q(t)

Current is the time-rate-of-change of charge. It is measured in Amperes

t t q

t i dt t it qt

conversely

Joule is a unit of energy

C

J V Voltage is a measure of energy/unit charge

If you add 1 Joule of energy to 1 Coulomb of charge, you haveincreased its voltage by 1 volt

Power is rate of energy transfers

J or WAV

chapter 1 linear circuit analysis

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