Download R-Electric-Circuits-Unit

Title of Unit
Curriculum Area
Developed By
Electric Circuit
Regular Physics
Shelly Gould Burgess
Grade Level
Time Frame
11 & 12
3.5-4 weeks
Identify Desired Results (Stage 1)
Content Standards
By the end of the unit, students will be able to…
1. relate the magnitude and direction of current to the rate of flow of charge.
2. determine the requirements of an electric circuit.
3. distinguish between alternating and direct current.
4. distinguish between electric field and electron drift velocity in a current-carrying medium.
5. determine the characteristics that affect resistance.
6. relate current, voltage, and resistance using Ohm’s Law.
7. draw circuits using conventional schematic symbols.
8. distinguish between the characteristics of series and parallel circuits.
9. perform calculations to analyze the current, equivalent resistance, and energy usage (“potential difference”; “voltage
drop”) across each resistor in a series, parallel, or mixed circuit.
10. evaluate electric power, current, and voltage in series, parallel, and mixed circuits.
Ohio Standards
DC Circuits
Once a circuit is switched on, the current and potential difference are experienced almost instantaneously in all parts of the circuit even though the
electrons are only moving at speeds of a few centimeters per hour in a current-carrying wire. It is the electric field that travels instantaneously through all
parts of the circuit, moving the electrons that are already present in the wire. Since electrical charge is conserved, in a closed system such as a circuit, the
current flowing into a branch point junction must equal the total current flowing out of the junction (junction rule). Resistance is measured in ohms and has
different cumulative effects when added to series and parallel circuits. The potential difference, or voltage (ΔV), across an energy source is the potential
energy difference (ΔE) supplied by the energy source per unit charge (q) (ΔV = ΔE/q). The electric potential difference across a resistor is the product of
the current and the resistance (ΔV = I R). In physics, only ohmic resistors will be studied. When potential difference vs. current is plotted for an Ohmic
resistor, the graph will be a straight line and the value of the slope will be the resistance. Since energy is conserved for any closed loop, the energy put
into the system by the battery must equal the energy that is transformed by the resistors (loop rule). For circuits with resistors in series, this means that
ΔVbattery = ΔV1 + ΔV2 + ΔV3 +…. The rate of energy transfer (power) across each resistor is equal to the product of the current through and the voltage drop
across each resistor (P = ΔV I) and Pbattery = I ΔV1 + I ΔV2 + I ΔV3 +… = IΔVbattery. Equations should be understood conceptually and used to calculate the
current or potential difference at different locations of a parallel, series or mixed circuit. However, the names of the laws (e.g., Ohm’s law, Kirchoff’s loop
law) will not be assessed. Measuring and analyzing current, voltage and resistance in parallel, series and mixed circuits must be provided. This can be
done with traditional laboratory equipment and through computer simulations.
Understandings
Essential Questions
Overarching Understanding
Students will understand the nature and behavior of
electric circuits.
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Related Misconceptions
Students often get confused about the relationships
between current, voltage, and resistance for series or
parallel circuits.
Overarching
Topical
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What is current?
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What is an electric circuit?
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What is electric resistance?
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What is Ohm’s Law?
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What is a series circuit?
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What is a parallel circuit?
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What is electric power?
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How does current relate to charge?
How do we measure current?
How fast does current flow?
What is drift speed?
What are the properties of alternating
current?
What are the properties of direct current?
What are the requirements for an electric
circuit?
What factors affect electric resistance?
How do we measure electric resistance?
What affect does electric resistance have on a
circuit?
What is the relationship between current,
resistance, and voltage in a circuit?
What are the characteristics of a series
circuit?
o How does voltage change at various
points in a series circuit?
o What are the characteristics of
current at various points in a series
circuit?
o How do we determine equivalent
(total) resistance in a series circuit?
What are the characteristics of a parallel
circuit?
o How does voltage change at various
points in a parallel circuit?
o What are the characteristics of
current at various points in a parallel
circuit?
o How do we determine equivalent
(total) resistance in a parallel circuit?
What is a short circuit?
How does electric power relate to current and
voltage?
How does electric power help us design wiring
for buildings?
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What are schematic diagrams?
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Knowledge
Skills
Students will know…
Students will be able to…
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what current is.
How can we communicate about circuits using
conventional paper-and-pencil models?
how to construct a series or parallel circuit.
how to use an ammeter and voltmeter.
how to calculate voltage drop across resistors for series or parallel
circuits.
 how to calculate current through each resistor for series or parallel
circuits.
 how to calculate equivalent (total) resistance for series or parallel
circuits.
From: Wiggins, Grant and J. Mc Tighe. (1998). Understanding by Design, Association for Supervision and Curriculum Development ISBN # 0-87120-313-8
(ppk)
Lesson 1
I. Objectives: Students will be able to…
1. relate the magnitude and direction of current to the rate of flow of charge.
2. determine the requirements of an electric circuit.
3. distinguish between alternating and direct current.
4. distinguish between electric field and electron drift velocity in a current-carrying medium.
5. determine the characteristics that affect resistance.
6. relate current, voltage, and resistance using Ohm’s Law.
7. draw circuits using conventional schematic symbols.
II. Materials:
 batteries, mini-light bulbs and sockets, wires, large broken light bulb with lateral wire visible, resistors of various Ohms,
ammeter, voltmeter
III. Procedure:
A. Hook: Lab activities on page 2 of flipchart
B. Notes and activities: pages 1-21
IV. Evaluation: Homework 1, evidence of flipchart work, quiz
Lesson 2
I. Objectives Students will be able to...
8. distinguish between the characteristics of series and parallel circuits.
9. perform calculations to analyze the current, equivalent resistance, and energy usage (“potential difference”; “voltage drop”) across
each resistor in a series, parallel, or mixed circuit.
II. Materials:
 batteries, mini-light bulbs and sockets, wires, large broken light bulb with lateral wire visible, resistors of various Ohms,
ammeter, voltmeter
III. Procedure: Notes and activities: pages 22-27
IV. Evaluation: Homework 2, evidence of flipchart work, quiz
Lesson 3
I. Objectives Students will be able to...
8. distinguish between the characteristics of series and parallel circuits.
9. perform calculations to analyze the current, equivalent resistance, and energy usage (“potential difference”; “voltage drop”) across
each resistor in a series, parallel, or mixed circuit.
II. Materials:
 batteries, mini-light bulbs and sockets, wires, large broken light bulb with lateral wire visible, resistors of various Ohms,
ammeter, voltmeter
III. Procedure: Notes and activities: pages 28-37
IV. Evaluation: Homework 3, evidence of flipchart work, quiz
Lesson 4
I. Objectives Students will be able to...
9. perform calculations to analyze the current, equivalent resistance, and energy usage (“potential difference”; “voltage drop”) across
each resistor in a series, parallel, or mixed circuit.
10. evaluate electric power, current, and voltage in series, parallel, and mixed circuits.
II. Materials:
 batteries, mini-light bulbs and sockets, wires, large broken light bulb with lateral wire visible, resistors of various Ohms,
ammeter, voltmeter
III. Procedure: Notes and activities: pages 38-45
IV. Evaluation: Homework 4, evidence of flipchart work, quiz