Download Coulomb`s Law Handout

Concept Presentation Summary
Candidate’s Names: Vandana Bathla and Magda Constantinescu
Title of the concept: Coulomb’s Law
Background Information to teach Coulomb’s Law:
- Every atom has positively charged nucleus around which much smaller particles called electrons
revolve.
- The nucleus is composed of two kinds of particles: protons and neutrons.
- A proton has just about the same mass as a neutron. However, a proton is about 2000 times as
massive as an electron.
- Protons and electrons are attracted to one another.
- Because of this force of attraction, elections "orbit" the nucleus much like the planets orbit the
sun.
- Two or more protons brought together will try and repel one another, but protons do not fly
apart because they are held together, along with the neutrons, by a much stronger force called
the strong nuclear force.
- Electrons also exhibit the property that when brought together, they repel one another.
- This force of attraction and repulsion is called the electrostatic force or electric charge.
- A proton is said to be positively charged and an electron negatively charged.
Like charges repel each other and unlike charges attract each other. "opposites attract"
Advance Preparation:
1) Teacher to demonstrate the activity to students before allowing them to perform this
activity.
2) Make students understand that safety is the first priority and properly demonstrate all the
safety procedures including the use of flash light appropriately and make sure that
students understand the safety rules for this activity.
3) Also teacher should make sure that every student has understood the activity by asking
random related question to students.
Special Materials:
1. Flash Light
2. Computer
Annotated References
1) Nelson, Physics 12
Student Difficulties:
1. Students may have difficulty in understanding coulomb law, so a good way to make sure the
success is to take a small prerequisite diagnostic activity.
2. In learning of problem-solving questions in coulomb’s law students frequently criticize these
exercises as nothing more than a little substitution with numeric data often presented in the same
order in which they fit into the proper formula. As a result, students develop a careless
methodology looking for the short response that will fill the blanks of a mathematical exercise
and require no thinking.
3. One alternative to solving such problems is as if they were small research projects, discarding
the use of numerical values in problems and thereby putting the emphasis on physics rather than
on mathematics. We can reword the problem to alter the goal of the exercise.
Teaching Ideas:
1. Coulomb Law will be taught through simulation activity.
2. Students will be given the handout to follow the instructions and complete the questions.
3. Students will be asked to apply Coulomb’s Law through problem solving.
Evaluation Procedure:
The students will be evaluated on the following:
1) Knowledge/Understanding
2) Making Connections
3) Thinking/Inquiry
4) Communication
Applications and Societal issues/Implications
1) Coulomb's law is one of the basic laws of physics (the science of matter and energy).
Anyone who studies electricity uses this principle over and over again. But Coulomb's
law is used in other fields of science as well. One way to think of an atom, for example, is
as a collection of electrical charges. Protons each carry one unit of positive electricity,
and electrons carry one unit of negative electricity. (Neutrons carry no electrical charge
and are, therefore, of no interest from an electrical standpoint.) Therefore, chemists (who
study atoms) have to work with Coulomb's law. How great is the force of repulsion
among protons in an atomic nucleus? How great is the force between the protons and
electrons in an atom? How great is the electrical force between two adjacent atoms?
Chemical questions like these can all be answered by using Coulomb's Law.
2) 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.
Lesson Sequence:
1. Expectations
2. Introduction –The Hook (10 min)
3. Activity: Part one (30 min)
4. Activity: Part two : (20 min)
5. Homework
6. Accommodations/ Modifications/Differentiated learning
7. Assessment
8. Credits
Annotated internet addresses:
http://phet.colorado.edu/
http://www.youtube.com/watch?v=b49DF-qN4n8&feature=related
http://www.scienceclarified.com/Co-Di/Coulomb.html#ixzz1RkCPFTHP
Student Name: _________________
Date: _________________
Coulomb’s Law - Simulation Activity
1. You need a partner and a computer. This is a group work but every student should
have their own handout to record the data collected during the simulation. Please
note that the teacher is going to review your handouts and your participation will
be recorded. Have fun!
2. Please follow the teacher’s instructions to begin the simulation.
a) Open the word document Simulation.doc located on the desktop and then Click on
the URL. http://phet.colorado.edu/en/simulation/charges-and-fields
b) Click on Run Now! An interactive simulation window will pop up. Look for:
-Positive charge– red (1nC ) and negative charge– blue (1nC ).
-E-fields sensors with orange that measure the force field.
Note: In the simulation the sensor measures the Force Field, not really the Force. We
are going to observe the Force Field (to get the force you just multiply the force field
times the charge.)
c) Check mark for the grid, for Show number and Show E-field. Look for:
-1m units for the grid
You are ready to start your simulation.
One red charge (the teacher can show some students how to place them on the grid)
Question: How does the electric force field caused by one charge vary with distance?
(a) Place one red charge on the grid at an intersection point
(b) Place on the grid 1 m away from the red charge one orange E-field sensor and
notice the field strength (the magnitude of the force field arrow)
(c) Increase the distance between charge and sensor and notice the field strength
Complete the table below:
One red charge
probe
Distance
1m
2m
3m
4m
Prediction
(Increasing or
Decreasing?
Force Field (V/m)
(record the value
from the screen)
Additional challenge simulations
Two red charges
Question: 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?
(a) Place two red charges on the grid at 1 m distance between each other.
(b) Place on the grid in the middle of the distance between the charges an orange Efield probe to measure the force field.
(c) Increase the distance between the two charges (always leaving the E-field sensor
in the middle between them)
Complete the table below:
Two red charge
probes
Distance
Prediction
Increasing or Decreasing
Force Field (V/m)
(record the value
from the screen)
1m
2m
3m
4m
One red and one blue charge
Question: How does the electric force field caused by two charges vary with distance?
What happens to the pattern of the force field when two charges are present?
(a) Place one red and one blue charge probes on the grid at 1 m distance between each
other.
(b) Place on the grid in the middle of the distance between the charges an orange Efield sensor to measure the force field.
(c) Increase the distance between the charge probes.
Complete the table below:
One red and one
blue charge
probes
Distance
Prediction
Increasing or Decreasing
1m
2m
3m
4m
Force Field (V/m)
(record the value
from the screen)