Download Unit 8

Subject: Physics
Timeframe Needed for Completion: 14 days
Grade Level: 11,12
Unit Title: Unit 8: Electricity
Grading Period: 2nd 9wks
New 2009 goals are in red
Big Idea/Theme: Static and Current Electricity
Understandings: Students will understand how static electricity if produced.
Students will understand how the electroscope works.
Students will understand how series and parallel circuits conduct electricity.
Students will understand voltage, amperes and electrical resistance in combination circuits.
Curriculum Goals/Objectives (to be assessed at the end of the unit/quarter)
Essential Questions:
Why do we get shocked in the winter when
3.1.1 Explain qualitatively the fundamental properties of the interactions of charged
objects.
touching metal objects?
• Identify basic principles related to the nature of electrical charge – like charges repel
How is electricity produced?
and opposite charges attract; there are two types of electric charge (positive and
What is an electrical circuit?
negative); positively charged objects have an electron deficiency while negatively
What is lightning?
charged objects have an excess of electrons.
• Conclude that charge is conserved in a closed system – since charge is a result of
fundamental properties of particles, charge (like atoms) cannot be created nor destroyed.
3.1.2 Explain the geometries and magnitudes of electric fields.
• Construct diagrams to illustrate electric fields and explain its vector nature:
around single positive and negative charges,
between a pair of like charges,
between a pair of unlike charges,
two oppositely charged parallel plates,
a hollow sphere,
an irregular shaped metal object.
• Compare the strength of various points in an electric field where
and for a point charge
for the uniform electric field between parallel plates. VEd=
• Distinguish between charge distribution on plates and a hollow conducting sphere where no
electric field exists inside.
3.1.3 Explain how Coulomb’s law relates to the electrostatic
charged objects.
interactions among
• Conceptually and mathematically explain electrical attraction and repulsion using Coulomb’s
law - the electrical force is directly
proportional to the product of two charges and inversely proportional to the square of the distance
between them, . 122ekqqFd=
• Determine the magnitude and direction of an electric force between two charges.
3.1.4 Explain the mechanisms for producing electrostatic charges including charging by
friction, conduction, and induction.
Explain situations where objects become charged (by friction, conduction or induction) in terms of
the transfer or rearrangement of electrons:
• two neutral objects charged by friction,
• a neutral object becoming positively charged by induction and conduction,
• a neutral object becoming negatively charged by induction and conduction.
3.1.5 Explain how differences in electrostatic potentials relate to the potential energy of
charged objects.
• Compare work done on an object by lifting (changes in location in a gravitational field) to work
done on a charged particle by pushing it
against the electric field of a charged object – both positive and negative.
• Define electric potential energy as the energy of a charge based on its location and distinguish
electric potential (voltage) as being the
same for all charges.
• Conclude that a gravitational field is always in one direction while electric fields have two
possible directions; by convention, the
direction is determined by the direction of force on a positive test charge – away from (out of) a
positive charge and toward (into) a
negative charge.
2.3.1
Explain Ohm’s law in relation to electric circuits.
• Recognize that a difference in potential (voltage) creates current within a conductor; the amount
of current also depends on the
resistance of the conductor.
• Develop a cause-and-effect model for current in a circuit - current is directly proportional to the
voltage and inversely proportional to
the resistance (Ohm’s law),
• Given a schematic circuit diagram, determine current, voltage, or resistance from two known
quantities.
2.3.2 Differentiate the behavior of moving charges in conductors and insulators.
• Identify conductors as materials that have electrons that are free to move throughout the sample;
Metals are good conductors of
electrical charge.
• Identify insulators as materials where electrons are held tightly to individual nuclei; Rubber and
glass are examples of insulators that
because of their properties develop static charge readily through friction with other materials.
• Explain classification as a conductor or insulator based on the ability of electric charge to move
through the material.
2.3.3 Compare the general characteristics of AC and DC systems without calculations.
Compare alternating and direct current systems based on the source of electrical energy,
transmission over distances, ease of use in varied
electrical devices, etc.
2.3.4 Analyze electric systems in terms of their energy and power.
• Develop the concept of power using dimensional analysis (unit cancellation) where electrical
power can be calculated from current,
voltage and/or resistance measurements,
• Since power is defined as the rate of work done or energy transferred, energy used by a device
can be calculated by multiplying power
and time,
2.3.5 Analyze systems with multiple potential differences and resistors connected in series
and parallel circuits, both conceptually and mathematically, in terms of voltage, current and
resistance.
• Analyze series circuits to distinguish the following patterns for current, voltage, and equivalent
resistance:
• Analyze parallel circuits to distinguish the following patterns for current, voltage, and equivalent
resistance:
current through each device equals
the current supplied
each branch is the same
reciprocals,
(Equivalent resistance in a parallel arrangement is lower than any one resistance in the
arrangement.)
• Conclude that multiple potential difference (voltage) sources are additive when arranged in
series; current moving from positive to
negative constitutes a negative potential difference. (e.g. - Two six volt batteries in series
connecting positive to negative terminals
have a combined potential difference of twelve volts; a six volt battery in series connecting
positive to positive terminals with a three
volt battery would establish a combined potential difference of three volts.) Network circuits
where a second emf is located in a
branch should not be included in the standard level course.
• Analyze series-parallel combination circuits by determining equivalent resistance of portions of
the circuit until it can be reduced to a
simple series or parallel circuit.
Essential Skills/Vocabulary:
 Conduct investigations involving static
electricity.
 Analyze the nature of electrical charge.
a. The two different kinds of electric charge
are defined as positive and negative.
b. Like charges repel and unlike charges
attract.
 Understand that matter is neutral when charges
are balanced and becomes charged when there
is a transfer of electrons.
 Recognize the three methods of charge transfer
are friction, conduction, and induction.
 Understand that electric charge is conserved
(neither created nor destroyed and may be
transferred from one object to another).
 Calculate the electrostatic force between any
two point charges using the equation:
kq1 q2
F 
d2
 Apply the inverse square relationship between
the force and the distance between the charges.
 Apply the proportional relationship between
the force and the product of the charges.
Cite evidence from experiments to support the
existence of two kinds of charge, the neutrality of most
matter, and explain charging by friction, conduction
and induction.
 Apply Ohm’s Law: V  IR
o Solve simple circuit problems.
Assessment Tasks:
Major test, quizzes, homework
Lab on Series Circuits
Lab on Parallel Circuits
Lab on Combination Circuits
Website on Electricity and Building Circuits
Rotational Lab
(Students rotate around 6 lab tables and observe electrical phenomena)
http://www.ncpublicschools.org/curriculum/science/scos/2004/27physics ( FOR
SUPPLIES NEEDED TO ACCOMPANY THE BELOW “INQUIRY SUPPORT
LABS”)
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Electrostatic lab-investigating electrostatics using common household items such as
making an electroscope from cellophane tape, balloons or pie pans
 Inquiry Support Lab: Sticky Tape Lab
 Current and resistance lab
 Inquiry Support Lab: Circuit Activity
 Inquiry Support Lab: Verifying Ohm’s Law
 Inquiry Support Lab: Ohm’s Law Activity
Inquiry Support Lab: Current and Voltage for Resistors in Series, Parallel, and
Mixed Circuits
Inquiry Support Lab: Voltage Activity
o Graph results from investigations.
 Observe how potential difference, current and
resistance affect the brightness of light bulbs in
circuits with batteries.
Design and conduct investigations to measure potential
difference and current in direct current circuits with
resistors and batteries.
Series circuits
 Recognize that current is the same throughout
the circuit: I t  I 1  I 2  I 3  ...
 Recognize that voltage divides proportionally
to the resistance. The sum of the voltage drops
across the circuit equals the potential difference
supplied to the circuit: Vt  V1  V2  V3  ...
 Calculate equivalent resistance:
R eq  R1  R 2  R 3  ...
 Apply Ohm’s law to series circuits.
Parallel circuits
 Recognize that current divides in inverse
proportion to the resistance. The sum of the
current through each device equals the current
supplied to the circuit: I t  I 1  I 2  I 3  ...
 Recognize that the voltage drop across each
branch is the same: Vt  V1  V2  V3  ...
 Calculate equivalent resistance:
1  1  1  1  ...
R eq R1 R 2 R 3
 Apply Ohm’s law to parallel circuits.
Combination circuits
 Calculate equivalent resistance.
 Develop a conceptual understanding of voltage
and current in a combination circuit.
AC/DC Systems
 Calculate and compare alternating and
direct current systems based on the source
of electrical energy.
Materials Suggestions:
http://www.ncpublicschools.org/curriculum/science/scos/2004/27physics ( FOR SUPPLIES NEEDED TO ACCOMPANY THE BELOW
“INQUIRY SUPPORT LABS”)
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Transparent tape
Soda can
Styrofoam cup.
Dry cell
Wire flashlight bulb
10 watt power resistors
6- 1.5 V dry cells
Ammeter
Voltmeter
One variable voltage DC power supply, one ammeter and one voltmeter (or two multimeters) per group of 2 – 4 students.
Various resistors.
Various connecting wires.
 Graphing software.
21st Century Skills
Communication
Skills
Conveying thought or
opinions effectively
When presenting
information,
distinguishing between
relevant and irrelevant
Activity

Analysis questions in all labs

Data collection in all Lab Activities
information
Explaining a concept
to others
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Sign Off—Sticky Tape lab
Circuit Activity
Ohm’s Law activity
 Sign Off—Sticky Tape lab
 Circuit Activity
Interviewing others or
being interviewed
Computer
Knowledge
Using word-processing
 Making graphs in labs
and database
programs
Developing visual
Sticky Tape Lab
aides for presentations
Using a computer for
 Sticky Tape
communication
 Ohm’s Law Activity
Learning new software
 Circuit Web link
programs
Employability Skills
Assuming
 Sticky Tape
responsibility for own
Activities
learning
 Sign Off –Circuit & Ohm’s law Activity
Persisting until job is
completed
Working independently
 Sticky Tape
Developing career
interest/goals
Responding to
 Sign Off –Sticky Tape
criticism or questions
 Ohm’s Law
Information-retrieval
Skills
Searching for
 Voltage Activity
information via the
computer
Searching for print
information
Searching for
information using
community members
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Current and Voltage for Resistors in Series &
Parallel
Current and Voltage for Resistors in Series &
Parallel
Language Skills Reading
Following written
directions
Identifying cause and
effect relationships
Summarizing main
points after reading
Locating and choosing
appropriate reference
materials
Reading for personal
learning
Language Skill Writing
Using language
accurately
Organizing and
relating ideas when
writing
Proofing and Editing
Synthesizing
information from
several sources
Documenting sources
Developing an outline
Writing to persuade or
justify a position
Creating memos,
letters, other forms of
correspondence
Teamwork
Taking initiative
Working on a team
Thinking/Problem-
Most of the activities can be presented as opportunities
for students to follow written directions. The teacher
will have to work with most students to develop this skill
over time.
 Sticky Tape
 Ohm’s Law
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All lab activities

“Explain” and “Evaluate” sections in all lab
activities
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Current and Voltage for Resistors in Series &
Parallel
Sign Off Activity
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Sign Off Activity
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All lab activities
Sign Off Activity
All lab activities
Sign Off Activity
Solving Skills
Identifying key
problems or questions
Evaluating results
Developing strategies
to address problems
Developing an action
plan or timeline
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All lab activities
Sign Off Activity
All lab activities
Sign Off Activity