Lab 2 Part 1 Electric Force XXXXXXXXXXName _____________________
Lab Goal: Introduce the formal mathematical form of Electric Force.
XXXXXXXXXXExamine the difference of understanding charge motion with Force vs Field
Lab 2 consists of a few simulations from PhET and from ophysics.com. These simulations will allow you to observe charge motion and effects. You will collect data and apply your plotting skills analytical skill of extracting numbers from your plots.
There are 3 parts to this lab:
Part 1. Electric Force PhET Coulomb’s Law
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/coulombs-law
Part 2. Electric Field PhET Charges and fields
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/charges-and-fields
Part 3. Combining a point charge and putting it into an Electric Fielld ophysics.com
XXXXXXXXXXCharged Particle in an Electric Field https:
ophysics.com/em6.html
There will be specific goals and instructions for each part. Please be sure to read everything.
For a general instruction, please play with the simulation before using it.
Remember to always reset the simulation window by clicking on the lower left corner.
Part 1. Electric Force PhET Coulomb’s Law
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/coulombs-law
Goal: The goal of the Coulomb’s Lab is
a. to study the parameters that affect the magnitude of the electric force.
b. to learn how to experimentally calculate the electric force constant.
Background: We learn new concepts in physics by observing how objects in the system are moving.
Experimentally we observe the objects, learn their characteristics, and watch the cause and effect as characteristics in the system are varied.
The system we are observing is a system with 2 charges.
The characteristic of the objects (= charges) is that they can have a (+) or (-) or(0) charge.
The parameters that can be varied are:
the magnitude of the charges
the distance between the charges
The cause and effect of the system is charge & distance effect the FORCE between these two objects.
Procedure: Part A Warm-up
Let’s pretend that we do not know the equation form of Coulomb’s Law.
We are just looking at the charges and scientifically playing with them.
Scientifically playing means that we are methodical about how we vary the two parameters (charge and distance) AND we record the measurements.
Note that in the simulation the FORCE is represented by the people holding the charge.
The magnitude of the FORCE is listed on the window. The direction of the FORCE is represented by vector on the charge. Remember: the two charges contribute to the magnitude of the FORCE. The direction of the FORCE depends on which charge you are observing.
Let’s examine this:
a. Set the sim-window so that q1 has a charge of +8 is located at 0 cm and q2 has a charge
of +5 located at 2 cm.
You should notice a coloration of the charges.
You should notice the people’s position (either a push or a pull).
Fill in the info about this configuration in the table below.
Then move q2 to another position and record your data.
Charge 1
Charge 2
Charge 2
charge
+8
+5
Position
0 cm
2 cm
Force, magnitude
Force, direction
People: push/pull?
direction
Repeat the above observation but replace Charge 2 with a –5
Charge 1
Charge 2
Charge 2
charge
+8
–5
Position
0 cm
2 cm
Force, magnitude
Force, direction
People: push/pull?
direction
Question: Why are the people “behaving” the way you are observing?
Procedure Part B: Effect of charge on the FORCE.
For this part, you will keep the distance between the charges the same. Put one charge at 2 cm and the other charge at 4 cm.
Vary the left and right charges as listed in the table below:
Left Charge
Right Charge
Distance interval
Resulting force (N)
1 μC
4 μC
4 μC
1 μC
2 μC
2 μC
1 μC
2 μC
1 μC
8 μC
2 μC
8 μC
Question 1: Compare the forces that each charged object feels from the other?
Question 2: Examine how the forces changed when you changed the charges. What can you conclude about the relationship of the 2 charges to the resulting force? (Hint: is it about the Sum? Difference? Product? Factor?)
Analysis: Plot the effect of the charges on the magnitude of the FORCE. (Force vs charge)
XXXXXXXXXXHow you plot this effect will depend on your answer to Question 2. Please insert your plot below.
Procedure Part C: Effect of distance between the charges on the FORCE.
For this part, you will keep the charges the same and vary the distance between the charges. Set the charges to be 5 μC. Place one charge at 0 cm. Move the other charge to the locations listed in the table below and record the resulting forces.
Left Charge
Right Charge
distance (cm)
resulting Force (N)
2
4
6
8
10
Question 1: Examine how the forces changed when you changed the distances. What can you conclude about the relationship of the distance between the 2 charges and the resulting force?
Analysis: Plot the effect of the distances between the charges on the magnitude of the FORCE. (Force vs distance)
Part 1 B I G Analysis:
You have explored the effect of the charges and the distances on the FORCE magnitude.
You have collected data on charge magnitude, distances, and forces.
You know that the equation for electric force, Coulomb’s force, is
In this experiment you have values for F, . In effect, the table of values are “measurements you took” of observational parameters. Basically, you observed
Now to calculate K. From alge
a (and our first lab) we learned how to plot data, fit a line to the data and get the slope of the (fitted) line using trendlines.
For this analysis you will make 2 plots and compute K and compare you value with the accepted value for K = 8.99 * 109 Nm2 / C2.
Use Procedure Part B for one plot and then use Procedure Part c for the other plot.
Compare both of these values with the actual value.
Lab 2 Part 2 Electric Field XXXXXXXXXXName _____________________
Lab Goal: Introduce the Field.
XXXXXXXXXXExamine the difference of understanding charge motion with Force vs Field
We continue with Lab 2 to examine and observe charge motion and effects. You will collect data and apply your plotting skills analytical skill of extracting numbers from your plots.
There are 3 parts to this lab:
Part 1. Electric Force PhET Coulomb’s Law
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/coulombs-law
Part 2. Electric Field PhET Charges and fields
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/charges-and-fields
Part 3. Combining a point charge and putting it into an Electric Fielld ophysics.com
XXXXXXXXXXCharged Particle in an Electric Field https:
ophysics.com/em6.html
There will be specific goals and instructions for each part. Please be sure to read everything.
For a general instruction, please play with the simulation before using it.
Remember to always reset the simulation window by clicking on the lower left corner.
Part 2. Electric Field PhET Charges and fields
XXXXXXXXXXhttps:
phet.colorado.edu/en/simulations/charges-and-fields
Goal: The goal of the Charges and Field Lab is to visualize how a charge alters space.
Background: We learn new concepts in physics by observing how objects in the system are moving.
Experimentally we observe the objects, learn their characteristics, and watch the cause and effect as characteristics in the system are varied.
We are beginning to understand that getting a detailed idea of how charges affect each other gets pretty complicated mathematically. But with the concept of Fields we have an easier time of this analysis.
Procedure: Part A Warm-up
Play with the “bells and whistles” of this simulation.
Keep in mind that the object in the Electric Field at a point in space is feels the Electric Force from the source object in the same direction as the field.
Procedure: Part B Point source charge
1. Drag and drop a +1 nC charge onto the middle of the Sim-Screen. Draw the field lines.
Note that relative field strength is indicated by the
ightness of the a
ows, not by thei
length, and that the field lines should be continuous (either originating on the source charge
or terminating on the source charge). (there are limits to sim-graphics ;-/ )
2. Clear the field and repeat the procedure with a -1 nC source charge.
3. Drag and drop an E-Field Sensor and place it in several random locations “around the face of the clock” (in the style of the spots below) at various distances from either sign source charge. Use the voltmeter to determine the electric potential at each location, labeling each spot as you go. Be sure to