Download Parallel Resistive Circuits Part 2

Parallel Resistive Circuits Part 2
Electronics
Lesson Plan
Performance Objective
At the end of the lesson, students will demonstrate the ability to apply problem solving and analytical
techniques to calculate parallel circuit electrical values by passing the Parallel Resistive Circuits Quiz.
Specific Objectives
 Identify a parallel resistive circuit
 Use current loops to determine electrical polarity
 Apply Kirchhoff’s Voltage Law to parallel circuits
 Apply Kirchhoff’s Current Law to parallel circuits
 Use Kirchhoff’s Law to derive circuit analysis tools
 Analyze circuits and calculate a variety of electrical values using the information given for
a parallel circuit
 Recite the formulas in the parallel circuit tool kit from memory
 Describe a step-by-step problem-solving process used for solving parallel circuit problems
 Solve a two resister parallel circuit for total resistance and total current
Terms
 Parallel Circuit- a circuit with more than one path for current flow
 Parallel Resistive Circuit- a parallel circuit containing only resistors
 Ohm’s Law- a formula that shows the mathematical relationship between current, voltage, and
resistance
 Kirchhoff’s Voltage Law- the sum of all voltages in a closed loop equals zero
 Kirchhoff’s Current Law- the sum of the currents into a node is equal to the sum of the currents
leaving the node
 Node- a branching point where current splits or combines
 Series Circuit- a circuit with only one path for current flow
 Voltage Drop- a voltage difference measured across a device
 Total Resistance- the equivalent resistance of the circuit; the resistance the battery sees
 Reciprocal- inverse; the one divided by x function
Time
It should take approximately two 50-minute periods to teach the lesson and go over the examples, two more
50-minute periods to work problems and analyze circuits through guided and independent practice, plus one
50-minute period for the quiz.
Copyright © Texas Education Agency, 2014. All rights reserved.
1
Preparation
TEKS Correlations
This lesson, as published, correlates to the following TEKS. Any changes/alterations to the activities may result
in the elimination of any or all of the TEKS listed.
Electronics
 130.368 (c)
o (5) The student implements the concepts and skills that form the technical knowledge of
electronics using project-based assessments. The student is expected to:
(C) demonstrate knowledge of the fundamentals of electronics theory;
(D) perform electrical-electronic troubleshooting assignments; and
(E) develop knowledge of voltage regulation devices.

130.368 (c)
o (6) The student applies the concepts and skills to simulated and actual work situations. The
student is expected to:
(A) measure and calculate resistance, current, voltage, and power in series, parallel, and
complex circuits; and
(D) demonstrate knowledge of common devices in optoelectronics.

130.368 (c)
o (8) The student learns the function and application of the tools, equipment, and materials used
in electronics through project-based assignments. The student is expected to:
(A) safely use tools and laboratory equipment to construct and repair circuits; and
(B) use precision measuring instruments to analyze circuits and prototypes.

130.368 (c)
o (9) The student designs products using appropriate design processes and techniques. The
student is expected to:
(A) interpret industry standard circuit schematics; and
(D) produce schematics to industry standards.
Interdisciplinary Correlations
Algebra I
 111.32 (b)
o (3) Foundations for functions. The student understands how algebra can be used to express
generalizations and recognizes and uses the power of symbols to represent situations. The
student is expected to:
(A) use symbols to represent unknowns and variables; and
(B) look for patterns and represent generalizations algebraically.
Copyright © Texas Education Agency, 2014. All rights reserved.
2
Geometry
 111.41 (c)
o (1) Mathematical process standards. The student uses mathematical processes to acquire and
demonstrate mathematical understanding. The student is expected to:
(A) apply mathematics to problems arising in everyday life, society, and the workplace; and
(B) use a problem-solving model that incorporates analyzing given information, formulating
a plan or strategy, determining a solution, justifying the solution, and evaluating the
problem-solving process and the reasonableness of the solution.
Occupational Correlation (O*Net – www.onetonline.org/)
Job Title: Electricians
O*Net Number: 47-2111.00
Reported Job Titles: Chief Electrician; Control Electrician; Electrician; Industrial Electrician; Inside Wireman;
Journeyman Electrician; Journeyman Wireman; Maintenance Electrician; Mechanical Trades Specialist,
Electrician; Qualified Craft Worker, Electrician (QCW, Electrician)
Tasks
 Plan layout and installation of electrical wiring, equipment, or fixtures, based on job specifications and
local codes.
 Connect wires to circuit breakers, transformers, or other components.
 Test electrical systems or continuity of circuits in electrical wiring, equipment, or fixtures, using testing
devices, such as ohmmeters, voltmeters, or oscilloscopes, to ensure compatibility and safety of system.
 Use a variety of tools or equipment, such as power construction equipment, measuring devices, power
tools, and testing equipment, such as oscilloscopes, ammeters, or test lamps.
 Inspect electrical systems, equipment, or components to identify hazards, defects, or the need for
adjustment or repair, and to ensure compliance with codes.
 Prepare sketches or follow blueprints to determine the location of wiring or equipment and to ensure
conformance to building and safety codes.
 Diagnose malfunctioning systems, apparatus, or components, using test equipment and hand tools to
locate the cause of a breakdown and correct the problem.
 Work from ladders, scaffolds, or roofs to install, maintain, or repair electrical wiring, equipment, or
fixtures.
 Advise management on whether continued operation of equipment could be hazardous.
 Maintain current electrician's license or identification card to meet governmental regulations.
Soft Skills
 Dependability
 Attention to Detail
 Integrity
 Analytical Thinking
 Initiative
 Leadership
 Self-Control
 Adaptability/Flexibility
 Persistence
Copyright © Texas Education Agency, 2014. All rights reserved.
3
Accommodations for Learning Differences
It is important that lessons accommodate the needs of every learner. These lessons may be modified to
accommodate your students with learning differences by referring to the files found on the Special
Populations page of this website.
Preparation
 Cover Parallel Resistive Circuits Part 1 as a prerequisite
 Parallel Resistive Circuits Part 1 and Part 2 are designed to be presented together
 Review the Parallel Resistive Circuits Part 2 slide presentation and lesson documents prior to each class
 Review and become familiar with the terminology and the example problems
 Have handouts and worksheets ready prior to the start of the lesson
References
 Roberts, Gerrish, and Dugger. (1999). Electricity & electronics. Tinley Park, Illinois: Goodheart-Willcox
Company.
 Mitchel E. Schultz. (2007). Grob’s basic electronics fundamentals of DC and AC circuits. Columbus, Ohio:
McGraw Hill.
Instructional Aids
 Tool Kit for Solving Parallel Circuit Problems Handout, summary of the “tool kit” and the
troubleshooting method
 Sample Problems With Two Resistors Worksheet, two resistor sample problems for guided and
independent practice (and key)
 Sample Problems With Three Resistors Worksheet, three resistor sample problems for guided and
independent practice (and key)
 Parallel Resistive Circuits Quiz (and key)
Introduction
The purpose of this lesson is to help students develop a systematic, step-by-step method to analyze circuits
and solve problems.

Ask
o Ok, so what have we learned so far?

Say
o We have learned some tools used to solve problems, and we have also learned about a step-bystep process for solving problems.
o We have also learned that solving problems is fun and exciting.

Say
o Now that we have had some experience solving parallel resistive circuits with two resistors, we
need to move on to those that are a little more complex
o This does not mean these problems are harder; it means we will have to focus on the process a
little bit more
o This means that we will be having a lot more fun, so let’s get started. (then begin presentation)
Copyright © Texas Education Agency, 2014. All rights reserved.
4
Outline
MI
OUTLINE
I.
II.
III.
More Complex Parallel Resistive Circuits (slides 15)
A. Looks at circuits with three paths for current
flow.
B. Follow the same procedure as the lesson with
two paths for current flow.
C. Apply Kirchhoff’s Law and solve first for
voltage dropped in each path, then for current
in each path.
D. Each path for current flow is separate and
independent.
Parallel Resistive Circuit Equations (slides 6-7)
A. One more term is added to each equation.
B. The concepts are exactly the same as a circuit
with two resistors.
C. Current from each parallel path adds to form
total current.
D. Parallel path voltage values are the same.
E. Resistance basically divides, but the major
concept is that total resistance goes down
each time a parallel path is added.
F. These concepts can be contrasted with the
way voltage works in a series circuit.
Understanding Resistance in a Parallel Circuit
(slides 8-11)
A. Lights are used to show how current increases
and resistance decreases in a parallel circuit.
B. This is like turning on lights in different rooms
in a house.
C. Turning on lights in one room does not affect
the lights in another room.
D. This is the same as the example from Part 1
except it shows a third switch and light.
E. Total current is three times the current for one
light and total resistance is one-third the
resistance of one light.
NOTES TO TEACHER
Show Parallel Resistive
Circuits Part 2 slide
presentation.
After presentation, have
students work practice
problems using both
guided and
independent practice.
Students start with
simple problems to
learn the formulas and
the step-by-step
process, and then they
work their way to more
difficult problems
designed to teach
problem-solving skills.
Note: equations
highlighted in a green
box are the “tools” for
parallel circuit analysis.
Equations highlighted in
a gray box are steps in
the problem-solving
sequence where
students need to enter
data or perform a
calculation.
Copyright © Texas Education Agency, 2014. All rights reserved.
5
MI
OUTLINE
IV.
V.
VI.
An Easier Way (slides 12-16)
A. Use the reciprocal button of a calculator to
simplify calculation of total resistance.
B. The reciprocal button is the one over x button.
C. The button is a little different among
calculators, but every calculator will have this
button in one form or another.
D. The first example is a two resistor example
from Part 1 to show that this method
calculates exactly the same value as before.
E. The second example uses three resistors and
mathematically demonstrates the total
resistance from the three light example.
Example Problems 1 and 2 (slides 17-25)
A. These problems are designed to allow students
to practice the easier method for calculating
total resistance.
B. Example one is the same example from Part 1;
students should get exactly the same value.
C. These problems are also designed to reinforce
the logical, step-by-step process to solve a
problem.
D. Allow students to perform the calculation
themselves before showing the solution.
E. Always start by writing down what the
problem is asking for and the equations
needed to solve for that value.
Example Problem Three (slides 26-32)
A. This is a slightly more difficult problem.
B. This example will reinforce the process that
students must take to solve a problem.
C. Again, prompt students to say the steps of the
process and the equations needed to solve it.
NOTES TO TEACHER
Emphasize that problem
solving is a skill
developed by practice.
Give students Handout
1 before going over
example Problem 1 in
the presentation.
The worksheets in
Handouts 2 and 3 can
be used for both guided
practice and
independent practice.
Problems 1 and 2 of
Worksheet 1 (Handout
2) are identical to
problems found in
Parallel resistive Circuits
Part 1. Students should
confirm that the
reciprocal method gives
exactly the same
answer.
Copyright © Texas Education Agency, 2014. All rights reserved.
6
MI
OUTLINE
NOTES TO TEACHER
VII. Example Problems 4 and 5 (slides 33-50)
A. These problems get progressively harder and
harder to solve.
B. Each problem adds one more step to the
process.
C. Students may not see how the answer can be
determined at first, but by following the
process, they can come up with an answer.
D. The process is the solution to the problem.
E. Each step is simple and logical.
F. Problem 5 introduces the concept that there
may be more than one correct way to solve a
problem, but there is always a process.
In each worksheet,
problems similar to
each of the examples
are grouped. Problems
3 and 4 in Sample
Problems With Two
Resistors Worksheet
are similar to Example 2
in the presentation.
Problems 5 and 6 are
similar to Example 3 in
the presentation, etc.
VIII. Parallel Circuit Equations For More Than Three
Paths (slides 51-54)
A. Extend the equations to use in any generic
case.
B. Each term in each equation is similar to the
others.
C. These formulas can be used with any number
of parallel resistance paths.
IX. Parallel Resistive Circuits Quiz
Have students work the
first problem of a
particular type using
guided practice
(Problems 3, 5, 7, and
10 in Sample Problems
With Two Resistors
Worksheet and
Problems 1, 5, 7, and 9
in Sample Problems
With Three Resistors
Worksheet). All other
problems should be
worked as independent
practice.
Each worksheet can be
done on a different day.
After students have
demonstrated
competence by
completing the
worksheets through
independent practice,
give the Parallel
Resistive Circuits Quiz
the next class day.
Copyright © Texas Education Agency, 2014. All rights reserved.
7
Multiple Intelligences Guide
Existentialist
Interpersonal
Intrapersonal
Kinesthetic/
Bodily
Logical/
Mathematical
Musical/Rhythmic
Naturalist
Verbal/Linguistic
Visual/Spatial
Application
Guided Practice
 Sample Problems With Two Resistors Worksheet (Problems 3, 5, 7, and 10) and Sample Problems With
Three Resistors Worksheet (Problems 1, 5, 7, and 9)
 Each of the problems listed is the first problem of a new type.
Independent Practice
 Sample Problems With Two Resistors Worksheet (Problems 1, 2, 4, 6, 8, 9, 11-14) (the problems get
progressively harder)
 Sample Problems With Three Resistors Worksheet Problems (2-4, 6, 8, 10-14)
Summary
Review
 Recite the formulas in the parallel circuit tool kit from memory.
 Describe a step-by-step, problem-solving process used for solving parallel circuit problems.
 Have students work problems of each type using independent practice.
Evaluation
Informal Assessment
The teacher will observe students solving problems and getting correct answers during independent practice.
Formal Assessment
The teacher will give the Parallel Resistive Circuits Quiz.
Enrichment
Extension
The students will be able to create their own problems for both two and three resister series circuits.
Copyright © Texas Education Agency, 2014. All rights reserved.
8
Tool Kit for Solving Parallel Circuit Problems
Handout
These three formulas (plus Ohm’s Law) make up the “Tool Kit” for solving parallel circuit
problems.
I T = I1 + I2 + I 3
VS = VR1 = VR2 = VR3
+
Summary of the step-by-step, problem-solving process:
1.
Write down what the problem is asking for.
2.
Write the formula(s) needed to solve for the value(s) that will solve the problem
from Step 1.
3.
If the values needed for the formula are given, plug them into the equation and
solve. If the values needed are not given, use one of the above “tools” to find a
formula to give what is needed.
4.
Repeat Step 3 as necessary until you are finally able to calculate a value that leads
to a solution. This process results in a sequence of problems that need to be
solved in order.
5.
Once you are able to solve for a value, plug that value into the previously
developed formula.
6.
Work your way back through the steps of the process developed in Steps 3 and 4
writing down each formula and solution.
7.
Highlight or circle the answer to the problem from Step 1.
Copyright © Texas Education Agency, 2014. All rights reserved.
9
Name_______________________________________Date_________________________Class____________
Sample Problems With Two Resistors
Worksheet
VS
R1
R2
1.
VS = 24 V, R1 = 10.56 kΩ, R2 = 8.8 kΩ, Solve for RT and IT
__________________________________________________
2.
VS = 14 V, R1 = 9.6 kΩ, R2 = 8.4 kΩ, Solve for RT and IT
___________________________________________________
3.
IT = 25 mA, R1 = 2 kΩ, R2 = 3 kΩ, Solve for Vs
___________________________________________________
4.
IT = 2.25 mA, R1 = 20 kΩ, R2 = 80 kΩ, Solve for Vs
___________________________________________________
5.
IT = 75 mA, R1 = 390 Ω, R2 = 624 Ω, Solve for I1 and I2
___________________________________________________
6.
IT = 3.25 mA, R1 = 2.4 kΩ, R2 = 8 kΩ, Solve for I1 and I2
__________________________________________________
7.
VS = 20 V, IT = 100 mA, I2 = 20 mA, Solve for R1
___________________________________________________
8.
VS = 12 V, IT = 4.1 mA, I1 = 2.5 mA, Solve for R2
__________________________________________________
9.
VS = 18 V, IT = 92.8 mA, I2 = 54.54 mA, Solve for R1
_________________________
10.
VS = 6 V, IT = 20 mA, R2 = 1.2 kΩ, Solve for R1
_________________________________
11.
VS = 9 V, IT = 3.33 mA, R2 = 4.2 kΩ, Solve for R1
_________________________________
12.
VS = 16 V, IT = 70.6 mA, R1 = 340 Ω, Solve for R2
_________________________
13.
R1 = 16 kΩ, I1 = 1.75 mA, I2 = 1.25 mA, Solve for R2
_________________________________
14.
IT = 27 mA, VS = 54 V, R1 = R, R2 = 2R, Solve for R1 and R2 __________________________________________________
Copyright © Texas Education Agency, 2014. All rights reserved.
10
Sample Problems With Two Resistors
Worksheet (KEY)
R1
VS
R2
1.
VS = 24 V, R1 = 10.56 kΩ, R2 = 8.8 kΩ, Solve for RT and IT (RT = 4.8 kΩ, IT = 5 mA)_______________
2.
VS = 14 V, R1 = 9.6 kΩ, R2 = 8.4 kΩ, Solve for RT and IT
(RT = 4480 Ω, IT = 3.125 mA)__________
3.
IT = 25 mA, R1 = 2 kΩ, R2 = 3 kΩ, Solve for Vs
(VS = 30 V)______________________________
4.
IT = 2.25 mA, R1 = 20 kΩ, R2 = 80 kΩ, Solve for Vs
(VS = 36 V)______________________________
5.
IT = 75 mA, R1 = 390 Ω, R2 = 624 Ω, Solve for I1 and I2
(I1 = 46.154 mA, I2 = 28.85 mA)______
6.
IT = 3.25 mA, R1 = 2.4 kΩ, R2 = 8 kΩ, Solve for I1 and I2 (I1 = 2.5 mA, I2 = 0.75 mA or 750 μA)
7.
VS = 20 V, IT = 100 mA, I2 = 20 mA, Solve for R1
(R1 = 250 Ω)____________________________
8.
VS = 12 V, IT = 4.1 mA, I1 = 2.5 mA, Solve for R2
(R2 = 7500 Ω)___________________________
9.
_
10.
VS = 18 V, IT = 92.8 mA, I2 = 54.54 mA, Solve for R1
(R1 = 470 Ω)____________________________
VS = 6 V, IT = 20 mA, R2 = 1.2 kΩ, Solve for R1
(R1 = 400 Ω)____________________________
11.
VS = 9 V, IT = 3.34 mA, R2 = 4.2 kΩ, Solve for R1
(R1 = 7.5 kΩ)___________________________
12.
VS = 16 V, IT = 70.6 mA, R1 = 340 Ω, Solve for R2
(R2 = 680 Ω)___________________________
13.
R1 = 16 kΩ, I1 = 1.75 mA, I2 = 1.25 mA, Solve for R2
(R2 = 22.4 kΩ)__________________________
14.
IT = 27 mA, VS = 54 V, R1 = R, R2 = 2R, Solve for R1 and R2
(R1 = 3 kΩ, R2 = 6 kΩ)_____________
Copyright © Texas Education Agency, 2014. All rights reserved.
11
Name_______________________________________Date_________________________Class____________
Sample Problems With Three Resistors
Worksheet
VS
R1
R3
R2
1.
VS = 8 V, R1 = 200 Ω, R2 = 400 Ω R3 = 400 Ω, Solve for RT and IT
____________________________________________
2.
VS = 15 V, R1 = 330 Ω, R2 = 470 Ω R3 = 250 Ω, Solve for RT and IT
____________________________________________
3.
VS = 15 V, R1 = 2.7 kΩ, R2 = 4.5 kΩ, R3 = 6.2 kΩ, Solve for RT and IT
___________________________________________________________
4.
VS = 9 V, R1 = 15 kΩ, R2 = 8.6 kΩ, R3 = 6 kΩ, Solve for RT and IT
____________________________________________
5.
IT = 25 mA, R1 = 4 kΩ, R2 = 4 kΩ, R3 = 2 kΩ, Solve for Vs
____________________________________________
6.
IT = 8 mA, R1 = 1.2 kΩ, R2 = 3.75 kΩ, R3 = 2 kΩ, Solve for Vs
___________________________________________
7.
IT = 20 mA, R1 = 1.5 kΩ, R2 = 3 kΩ, R3 = 2 kΩ, Solve for I1, I2, and I3
____________________________________________
8.
IT = 15 mA, R1 = 4 kΩ, R2 = 12 kΩ, R3 = 6 kΩ, Solve for I1, I2, and I3
____________________________________________
9.
VS = 20 V, IT = 100 mA, I2 = 20 mA, I2 = 30 mA, Solve for R1
____________________________
10.
VS = 35 V, IT = 20 mA, I2 = 10.89 mA, I3 = 5.93 mA, Solve for R1
____________________________
11.
VS = 18 V, IT = 6.2 mA, R1 = 15 kΩ, R3 = 9 kΩ, Solve for R2
____________________________
12.
VS = 10 V, IT = 69.5 mA, R1 = 330 Ω, R3 = 560 Ω, Solve for R2
____________________________
13.
IT = 11.1 mA, R1 = 14.4 kΩ, I1 = 2.5 mA, R3 = 10 kΩ, Solve for R2
____________________________
14.
V1 = 9 V, R1 = 3 kΩ, I2 = 2.5 mA, I3 = 3.6 mA, Solve for R2 and R3
___________________________________________
Copyright © Texas Education Agency, 2014. All rights reserved.
12
Sample Problems With Three Resistors
Worksheet (KEY)
VS
R1
R2
R3
1.
VS = 8 V, R1 = 200 Ω, R2 = 400 Ω, R3 = 400 Ω, Solve for RT and IT
(RT = 100 Ω, IT = 80 mA)______________
2.
VS = 15 V, R1 = 330 Ω, R2 = 470 Ω, R3 = 250 Ω, Solve for RT and IT (RT = 109.2 Ω, IT = 137.37 mA)______
3.
VS = 15 V, R1 = 2.7 kΩ, R2 = 4.5 kΩ, R3 = 6.2 kΩ, Solve for RT and IT (RT = 1326.5 Ω, IT = 11.3 mA)________
4.
VS = 9 V, R1 = 15 kΩ, R2 = 8.6 kΩ, R3 = 6 kΩ, Solve for RT and IT
(RT = 2.86 kΩ, IT = 3.15 mA)_________
5.
IT = 25 mA, R1 = 4 kΩ, R2 = 4 kΩ, R3 = 2 kΩ, Solve for Vs
(VS = 25 V)_____________________________
6.
IT = 8 mA, R1 = 1.2 kΩ, R2 = 3.75 kΩ, R3 = 2 kΩ, Solve for Vs
(VS = 5 V)_______________________________
7.
IT = 20 mA, R1 = 1.2 kΩ, R2 = 3 kΩ, R3 = 2 kΩ, Solve for I1, I2, and I3 (I1 = 10 mA, I2 = 4 mA, I3 = 6 mA)__
8.
IT = 15 mA, R1 = 4 kΩ, R2 = 12 kΩ R3 = 6 kΩ, Solve for I1, I2, and I3 (I1 = 7.5 mA, I2 = 2.5 mA, I3 = 5 mA)_
9.
VS = 20 V, IT = 100 mA, I2 = 20 mA, I3 = 30 mA, Solve for R1
(R1 = 400 Ω)___________________________
10.
VS = 35 V, IT = 20 mA, I2 = 10.89 mA, I3 = 5.93 mA, Solve for R1
(R1 = 11 kΩ)___________________________
11.
VS = 18 V, IT = 6.2 mA, R1 = 15 kΩ, R3 = 9 kΩ, Solve for R2
(R2 = 6 kΩ)_____________________________
12.
VS = 10 V, IT = 69.5 mA, R1 = 330 Ω, R3 = 560 Ω, Solve for R2
(R2 = 470 Ω)____________________________
13.
IT = 11.1 mA, R1 = 14.4 kΩ, I1 = 2.5 mA, R3 = 10 kΩ, Solve for R2
(R2 = 7.2 kΩ)___________________________
14.
V1 = 9 V, R1 = 3 kΩ, I2 = 2.5 mA, I3 = 3.6 mA Solve for R2 and R3 (R2 = 3.6 kΩ, R3 = 2.5 kΩ)_____________
Copyright © Texas Education Agency, 2014. All rights reserved.
13
Name_______________________________________Date_________________________Class____________
Parallel Resistive Circuits Quiz
1. How do you identify a parallel circuit?
A
B
C
D
Only one path for current flow
Multiple paths for current flow
Multiple circuit voltages
Multiple circuit resistances
2. The voltage across each parallel resistor
A
B
C
D
Is equal to the ratio of the resistance
Is equal to the ratio of the currents
Is the same
Cannot be determined
3. Kirchhoff’s current law states:
A
B
C
D
The ratio of current at a node is equal to the ratio of resistance
The total current into a node equals the total resistance out of the junction
The ratio of the voltages equals the ratio of the resistances
The sum of the currents into a node equals the sum of the currents out
4. When additional resistors are connected in parallel, total resistance
A
B
C
D
Increases
Decreases
Stays the same
Cannot be determined
5. A parallel circuit acts like a
A
B
C
D
Current divider
Voltage divider
Resistance divider
Voltage source
6. When there is an open circuit in one parallel branch
A
B
C
D
Voltage increases
Voltage decreases
Other branch currents stay the same
Other branch currents decrease
Copyright © Texas Education Agency, 2014. All rights reserved.
14
7. A parallel circuit has the following resistances: R1 = 390 Ω, R2 = 560 Ω, R3 = 820 Ω. Which resistor
has the least current?
A
B
C
D
R1
R2
R3
They all have the same current
8. A parallel circuit has the following currents: IT = 110 mA, I1 = 20 mA, I3 = 40mA, I2 = _____.
A
B
C
D
20 mA
40 mA
50 mA
60 mA
9. Four resisters are connected in parallel. IT = 50 mA, I1 = 15 mA, I4 = 25 mA, and R2 = R3. What is the
current through R3?
10. The following resistors are connected in parallel. R1 = 1 kΩ, R2 = 2.2 kΩ, R3 = 4.7 kΩ. What is RT?
11. The following resistors are connected in parallel. R1 = 3.3 kΩ, R2 = 4.7 kΩ, R3 = 6.8 kΩ. What is RT?
Copyright © Texas Education Agency, 2014. All rights reserved.
15
12. In a parallel circuit, R1 = R2 = R3 and RT = 3.3 MΩ. What is R1?
13. In the following circuit, what is IT?
VS =
15 V
R1 =
R2 =
R3 =
20 kΩ
20 kΩ
40 kΩ
14. In the following circuit, what is VS?
VS =
?
IT = 86 mA
R1 =
1.5 kΩ
R2 =
300 Ω
Copyright © Texas Education Agency, 2014. All rights reserved.
16
15. In the following circuit, what is R1?
VS =
IT = 1.36 mA
R1 =
20 V
R2 =
?Ω
32.3 kΩ
R2 =
R2 =
16. In the following circuit, what is R2?
IT = 6.18 mA
VS =
32 V
6.6 kΩ
? kΩ
Copyright © Texas Education Agency, 2014. All rights reserved.
17
Parallel Resistive Circuits Quiz
(KEY)
1. How do you identify a parallel circuit?
A
B
C
D
2.
Only one path for current flow
Multiple paths for current flow
Multiple circuit voltages
Multiple circuit resistances
The voltage across each parallel resistor
A
B
C
D
Is equal to the ratio of the resistance
Is equal to the ratio of the currents
Is the same
Cannot be determined
3. Kirchhoff’s current law states
A
B
C
D
4.
When additional resistors are connected in parallel, total resistance
A
B
C
D
5.
Increases
Decreases
Stays the same
Cannot be determined
A parallel circuit acts like a
A
B
C
D
6.
The ratio of current at a node is equal to the ratio of resistance
The total current into a node equals the total resistance out of the junction
The ratio of the voltages equals the ratio of the resistances
The sum of the currents into a node equals the sum of the currents out
Current divider
Voltage divider
Resistance divider
Voltage source
When there is an open circuit in one parallel branch
A
B
C
D
Voltage increases
Voltage decreases
Other branch currents stay the same
Other branch currents decrease
Copyright © Texas Education Agency, 2014. All rights reserved.
18
7.
A parallel circuit has the following resistances: R1 = 390 Ω, R2 = 560 Ω, R3 = 820 Ω. Which
resistor has the least current?
A
B
C
D
8.
A parallel circuit has the following currents: IT = 110 mA, I1 = 20 mA, I3 = 40mA, I2 = _____.
A
B
C
D
9.
R1
R2
R3
They all have the same current
20 mA
40 mA
50 mA
60 mA
Four resisters are connected in parallel. IT = 50 mA, I1 = 15 mA, I4 = 25 mA, and R2 = R3. What is
the current through R3?
5 mA
10. The following resistors are connected in parallel. R1 = 1 kΩ, R2 = 2.2 kΩ, R3 = 4.7 kΩ. What is RT?
600 Ω
11. The following resistors are connected in parallel. R1 = 3.3 kΩ, R2 = 4.7 kΩ, R3 = 6.8 kΩ. What is
RT?
1508.6 Ω
Copyright © Texas Education Agency, 2014. All rights reserved.
19
12. In a parallel circuit, R1 = R2 = R3 and RT = 3.3 MΩ. What is R1?
1.1 MΩ
13. In the following circuit, what is IT?
VS =
15 V
R1 =
R2 =
R3 =
20 kΩ
20 kΩ
40 kΩ
1.875 mA
14. In the following circuit, what is VS?
I = 86 mA
VS =
?
T
R1 =
1.5 kΩ
R2 =
300 Ω
21.5 V
Copyright © Texas Education Agency, 2014. All rights reserved.
20
15. In the following circuit, what is R1?
VS =
IT = 1.36 mA
20 V
R1 =
R2 =
?Ω
32.3 kΩ
R2 =
R2 =
27 KΩ
16. In the following circuit, what is R2?
IT = 6.18 mA
VS =
32 V
6.6 kΩ
? kΩ
24 KΩ
Copyright © Texas Education Agency, 2014. All rights reserved.
21