Download Activity 1.2.2 Circuit Theory

Activity 1.2.2 Circuit Theory – Hand
Calculations
Introduction
Have you ever used a calculator to add some numbers, looked at the answer, and
realized that it was wrong? How did you know that the answer was incorrect? The
calculator gave you an answer; why did you not trust it? You knew the answer was
wrong because you understand the fundamentals of mathematics. Your instinct told
you that the answer could not be correct.
The same is true for circuit analysis. Throughout this course you will be using a
Circuit Design Software to test the circuits that you design. This software will always
give an answer, right or wrong. The only way that you will be able to rely on these
answers is if you have an understanding of the laws of circuit analysis. You must
develop the same instinct for circuit behavior that you have for mathematics.
In this activity you will gain experience applying Ohm’s Law and Kirchhoff’s Voltage
and Current Laws to solve simple series and parallel circuits.
Equipment
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Paper & pencil
Calculator
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DE – Unit 1 – Lesson 1.2 – Activity 1.2.2 – Circuit Theory: Hand Calculations – Page 1
Procedure
1. For each of the resistors shown below, use Ohm’s Law to calculate the unknown
quantity. Be sure to put your answer in proper engineering notation and use the
correct units.
2. For each of the circuits shown below, calculate the value for RT. Be sure to put
your answer in proper engineering notation and use the correct units.
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3. Using the laws of circuit theory, solve for RT, IT, VR1, VR2, & VR3. Be sure to put
your answer in proper engineering notation and use the correct units.
Using the data from problem (3), verify your results using Kirchhoff’s Voltage
Law.
4. Using the laws of circuit theory, solve for RT, IT, VR1, VR2, VR3, & VR4. Be sure to
put your answer in proper engineering notation and use the correct units.
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DE – Unit 1 – Lesson 1.2 – Activity 1.2.2 – Circuit Theory: Hand Calculations – Page 3
Using the data from problem (4), verify your results using Kirchhoff’s Voltage
Law.
5. Using the laws of circuit theory, solve for RT, IT, IR1, IR2, & IR3. Be sure to put your
answer in proper engineering notation and use the correct units.
Using the calculated results from problem (5), verify your results using Kirchhoff’s
Current Law.
6. Using the laws of circuit theory, solve for RT, IT, IR1, IR2, IR3, & IR4. Be sure to put
your answer in proper engineering notation and use the correct units.
Using the calculated results from problem (6), verify your results using Kirchhoff’s
Current Law.
Project Lead The Way, Inc.
Copyright 2009
DE – Unit 1 – Lesson 1.2 – Activity 1.2.2 – Circuit Theory: Hand Calculations – Page 4
Conclusion
1. State two rules for the voltage and current in a series circuit.
2. State two rules for the voltage and current in a parallel circuit.
3. If you remove a single bulb from an inexpensive string of Christmas tree lights, all
of the lights in the entire string will go off. Are the bulbs connected in series or
parallel? Explain.
Going Further – Optional
The circuit shown below is a series/parallel circuit. That is, some of its resistors are
connected in series and some are in parallel. Using the laws of circuit theory, solve
for RT & IT.
Project Lead The Way, Inc.
Copyright 2009
DE – Unit 1 – Lesson 1.2 – Activity 1.2.2 – Circuit Theory: Hand Calculations – Page 5