Concept Presentation
Coulomb’s Law
3/15/2016
by Vandana Bathla and Magda
Constantinescu
1
Introduction
 Welcome
3/15/2016
to our Concept Presentation!
by Vandana Bathla and Magda
Constantinescu
2
Introduction
We have an experiment to show you.
Please form a pair for Think/Pair/Share.
Materials: Flashlight, stick meter
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by Vandana Bathla and Magda
Constantinescu
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Introduction
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I position the flashlight at 1 m distance the wall.
Please observe the area of light projected on the wall.
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If I move the flashlight at 2 m distance the wall.
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How big the area of light is going to be?
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Think/Pair/Share with your partner: Predictions!
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by Vandana Bathla and Magda
Constantinescu
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Introduction
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What happens with the intensity of light, is it increasing or
decreasing?
Whole group discussion!
by Vandana Bathla and Magda
Constantinescu
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Introduction
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Conclusion:
The intensity of light has an inverse-square dependence on
distance between the source of light and the wall.
by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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Textbook definition:
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The force between two point charges is inversely proportional to
the square of the distance between the charges and directly
proportional to the product of the charges. (Nelson, Grade 12)
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k –proportionality constant
Q1 and Q2 – magnitudes of the charges
d – distance between them
by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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Coulomb’s Law applies when the charges on two
spheres are very small and the two spheres are small
compared to the distance between them.
Electric charge is measured in units called coulombs
(SI unit, C) (Nelson, Grade 12)
by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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The forces act along the line connecting the two point
charges. (Nelson, Grade 12)
The charges will repel if the forces are alike and
attract if unlike. (Nelson, Grade 12)
by Vandana Bathla and Magda
Constantinescu
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Misconceptions/Difficulties
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The students may do not understand that “all the matter around us contains
charged particles, and it is the electric forces between these charged particles
that determine the strength of the materials and the properties of the substance.”
(Nelson, Grade 12)
The students may have difficulties in understanding Coulomb’s Law, so the
teacher is going to do a diagnostic activity.
During the activity the teacher observes and takes anecdotal notes. This activity
has to be done at the beginning of the unit.
by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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Applications:
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Coulomb’s law is employed in meteorology to test models of
thunderstorm charge distributions.
Atmospheric physics, planetary physics, astrophysics, and plasma
physics are vast domains of application of coulomb’s law.
Another application of Coulomb's law is in the study of crystal
structure. Crystals are made of charged particles called ions. Ions
arrange themselves in any particular crystal (such as a crystal of
sodium chloride, or table salt) so that electrical forces are balanced. By
studying these forces, mineralogists can better understand the nature of
specific crystal structures.
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
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Expectations
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D2.1 use appropriate terminology related to fields, including, but not limited to: forces, potential energies,
potential, and exchange particles [C]
D2.5 conduct a laboratory inquiry or computer simulation to examine the behaviour of a particle in a field
(e.g., test Coulomb’s law; replicate Millikan’s experiment or Rutherford’s scattering experiment; use a bubble
or cloud chamber) [PR]
D3.2 compare and contrast the corresponding properties of gravitational, electric, and magnetic fields (e.g., the
strength of each field; the relationship between charge in electric fields and mass in gravitational fields)
A1.10 draw conclusions based on inquiry results and research findings, and justify their conclusions with
reference to scientific knowledge
A1.11 communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic
presentations, using appropriate language and a variety of formats (e.g., data tables, laboratory reports,
presentations, debates, simulations, models)
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UNIT 3: Electric, Gravitational, and Magnetic Fields; Electric Forces: Coulomb’s Law
(Nelson, Physics 12)
Resources: http://phet.colorado.edu/, (Nelson, Physics 12)
Learning/Teaching Strategies: demonstration, inquiry computer simulation, small groups, Venn
Diagram
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Safety Considerations: The teacher does the demonstration with the flashlight and the activity is a
computer simulation. The teacher has to use the flashlight carefully.
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
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Resources: http://phet.colorado.edu/, (Nelson, Physics 12)
The resources have be reliable and teacher and students have access to
them.
Learning/Teaching Strategies: demonstration, inquiry computer
simulation, small groups, Venn Diagram
Safety Considerations: The teacher does the demonstration with the
flashlight and the activity is a computer simulation. The teacher has to
use the flashlight carefully.
Materials: Flashlight, meter stick, manipulative (planets), visual adds,
handouts
by Vandana Bathla and Magda
Constantinescu
13
Lesson Overview
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A. Introduction –The Hook (10 min)
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I will do the same demonstration as we did at the beginning.
Students will make comments like: the intensity is decreasing and has an inversesquare dependence on distance between the source and wall.
If the students are not coming with this conclusion as a facilitator I will highlight
the conclusion.
At this point I will mention to students that today we are going to learn about
Coulomb’s Law.
I will make a parallel connections with Coulomb’s Law.
I will write on the board the conclusion from the introduction and I will draw a
diagram where on the wall is a charge #1 and on the flashlight is a charge #2, and
the distance between the wall and flashlight is r.
Then I will present the Coulomb’s Law
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
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B. Activity:
Part one (30 min)
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I will tell them that we are going to do a simulation on the computer and they are
going to work in pairs and use the handout to record all the data.
I pair the students, so that the student who knows the most is with the student who
knows the least.
After every group is ready to start the simulation I will demonstrate to the whole
class the first steps:
1. Click on the URL. http://phet.colorado.edu/en/simulation/charges-and-fields
from the word document Simulation.doc located on the desktop.
2. Click on the Run Now!
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
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Part one (30 min)
3. An interactive simulation window will pop up and I present them the elements they are
going to use for the simulation.
4. I ask them to follow my instructions to get familiar with the simulation window.
5. I show them an example and I ask them if they have any questions before starts the
simulation.
6. I invite students to follow the instruction in the Handout and to record the data.
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Before they start I remind them that with this activity we are going to answer the
following questions:
How does the electric force field caused by two red charges vary with distance?
What happens to the pattern of the force field when two charges are present?
Note: In the simulation the sensor measure the Force Field, no really the Force. To get the force you just multiply the force field times the
charge.
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
Part one (30 min)
7. After completing the handouts I ask students to come with an answer to the question
posted on the board.
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8. As a class we have a discussion about the law and write the formula on the board.
I invite students to write the definition and formula in their science notebook.
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9. As an application of the law I will model a practice sample from the textbook and
then in groups of two they have to practice another one. Homework will be
assigned from the textbook.
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
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Part two : (20 min)
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I will show students two planets and I ask them about the force between
them.
I will expect to answer Law of Universal Gravitation. I will write the
definition and the formula on the board.
I will write the following question on the board and I ask them to work in
groups.
Knowing the two laws please use a Venn Diagram to answer the
questions: How are they different? How are they similar?
I will collect the Venn Diagrams to assess their understanding of the
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concept.
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by Vandana Bathla and Magda
Constantinescu
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Lesson Overview
C. Homework: Students have to research real life applications of the Coulomb Law
and show their knowledge in the form of a graphic organizer or essay.
D. Accommodations/ Modifications/Differentiated learning:
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I will pair the students, so that the student who knows the most is with the student
who knows the least.
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The handout is design to help students with learning disability to follow the
instruction.
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ELL –students: I will design the handout using pictures with the windows from the
simulation.
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Venn Diagram: I group students using Tiered Assessment and Flexible grouping
strategies.
E. Assessment: Handouts, anecdotal notes, Venn Diagram, problem-solving,
differentiated assessment (essay or graphic organizer)
F. Credits: http://phet.colorado.edu/en/simulation/charges-and-fields,
(Nelson textbook, Grade 12)
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by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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3/15/2016
Time for a 5 min break!
by Vandana Bathla and Magda
Constantinescu
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Computer Simulation
We are going to do the same simulation that we mentioned in the
lesson. (10 min)
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What do you need:
Handout, computer and a partner
Questions for Discussion:
How did you find this simulation?
Are you going to use this simulation in the classroom?
by Vandana Bathla and Magda
Constantinescu
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Coulomb’s Law
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3/15/2016
Thank you for your participation!
by Vandana Bathla and Magda
Constantinescu
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