This simulation shows a large metal conductor (in grey) that can be given many extra electrons. Play with the simulation for a few minutes and write down your observations.
Overview
Students use previously developed rules of charge interaction (sticky tape lab exploration) to examine the behavior of charge on conductors. They will work through a simulation with only one conductor (circle or square shaped), and then two conductors that can move around and exchange excess charge. Finally, they will examine behavior of an insulator using the PhET balloon simulation.
Standards
Next Generation Science Standards
- Physical Science
- [HS-PS2] Motion and Stability: Forces and Interactions
- [HS-PS2-4] Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects.
- [HS-PS3-5] Develop and use a model of two objects interacting through electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction.
- NGSS Practice
- Using Models
- Arguing from Evidence
- Conducting Investigations
- Analyzing Data
- Constructing Explanations, Designing Solutions
- NGSS Crosscutting Concept
- Systems
Computational Thinking in STEM
- Data Practices
- Analyzing Data
- Collecting Data
- Creating Data
- Manipulating Data
- Visualizing Data
- Modeling and Simulation Practices
- Assessing Computational Models
- Designing Computational Models
- Using Computational Models to Understand a Concept
- Constructing Computational Models
- Computational Problem Solving Practices
- Computer Programming
- Preparing Problems for Computational Solutions
Credits
Dan DuBrow & Emily Habbert
Acknowledgement
NetLogo charge models: Jacob Kelter, Northwestern University
NetLogo software:
- Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
PhET Simulation, Balloons & Static Electricity: https://phet.colorado.edu/en/simulation/balloons
| Design Team | Third-party Libraries | Thanks To |
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Activities
- 1. One Conductor -- Electron Behavior
- 2. Two Conductors -- Electron Behavior
- 3. Insulators -- Charge Behavior
Student Directions and Resources
- Students will be able to explain the factors that affect electron movement within a conductor.
- Students will be able to accurately describe electron movement when two conductors come into contact.
- Students will be able to explain how charge behavior differs in insulators.
- Students will be able to explain why a charged object attracts a neutral object.
1. One Conductor -- Electron Behavior
During our sticky tape lab, we investigated the behavior of B and T tapes as well as several other types of objects. Let's take a look at a simulation that can help us think about what individual charges are doing on metal conductors (note: we will talk about how B and T tapes might behave a bit later).
To run the simulation, adjust the settings for shape, size, and number of electrons, then click "setup" and then click "go". If you need to change the speed of the simulation, pull the slider on the bar labeled "ticks" at the top. When you're ready to start a new trial, again adjust settings, click setup, and go.
Question 1.1
Question 1.2
Talk with a neighbor and brainstorm what rules seem to be guiding the electrons' behavior/movement. Record your answers.
Question 1.3
Do you notice any difference between how the electrons move for the square conductor as compared to the circle conductor? Why do you think the electrons are behaving in this way?
Hint: Try this with a relatively small number of charges.
Question 1.4
Set the conductor to be a circle, and then let the simulation run for a while. You can move the "ticks" slider to the right to make it run faster. What do you notice if you let the simulation run for a very long time?
Question 1.5
Now run the simulation several times (with either shape, but don't change it during these trials), keeping the "n-electrons" constant, but changing the "side-length" to different values several times. Record your observations about how the electrons behave as the side-length changes.
Question 1.6
Now run the simulation several times (with either shape, but don't change it during these trials), keeping the side length constant but varying the number of electrons. What do you notice about what happens as the number of electrons changes?
Question 1.7
Throughout the questions above, you should have noticed that the electrons spread out and move to the surface of the conductor. Why do you think this occurs? Additionally, summarize what patterns you observe when shape and electron number changes.
Question 1.8
Any computer simulation is written with a number of assumptions and simplifications in mind. Can you think of ways that this simulation does not accurately represent what happens in real life in a metal?
Hint: draw on your Chemistry knowledge
Question 1.9
Now click on the "NetLogo Code" tab below the simulation. Can you figure out a way to change the color of the conductor from grey to red? In order to test your solution, you will need to click the button, "Recompile Code."
Hint: you can type Ctrl-F to find all the places in the code where the word "grey" is used. Maybe that has something to do with the color used? :)
What are you talking about?
Sure can!
Sure can!
2. Two Conductors -- Electron Behavior
Now we will look at the interaction of two charged metal conductors, and see if we can observe any patterns.
To run the simulation, adjust the settings for shape, size, and number of electrons, then click "setup" and then click "go". If you need to change the speed of the simulation, pull the slider on the bar labeled "ticks" at the top. When you're ready to start a new trial, again adjust settings, click setup, and go.
Question 2.1
Create 2 square conductors of equal size and with equal excess charge. Click setup and go, and then wait until the charge (mostly) stops moving. What do you notice about the arrangement of charges in each square?
Hint: you can increase the model speed using the slider at the top of the simulation.
Question 2.2
Move the two squares you just created close together but NOT touching. Did the electrons move from their previous positions? Does their final stable position differ from before (Q2.1)? Why or why not?
Hint: Slow the tick slider down significantly before moving the squares so you don't miss what happens!
Question 2.3
Now touch the two squares together. What happens? Why do you think this occurs?
Question 2.4
Repeat this same sequence (Q2.1-Q2.3), but with circle conductors instead of squares. Does anything happen differently when the circles are originally created (Q2.1), moved close together but not touching (Q2.2), or touched together (Q2.3)?
Question 2.5
Set up 2 conductors (of either shape) with equal charge, but significantly different sizes. What happens to the electrons when you touch these two conductors together? Explain what the final arrangement of charges looks like and why it ends up this way.
Question 2.6
Set up 2 conductors (of either shape) with equal sizes, but significantly different charges. What happens to the electrons when you touch these two conductors together? Explain what the final arrangement of charges looks like and why it ends up this way.
Question 2.7
Again, keep the size of the conductors the same and the initial number of electrons different. Touch the conductors together, and wait for the charges to stabilize. Below, record:
- How many electrons started on each object?
- How many electrons ended on each object?
- How many electrons moved?
- Is there a pattern or "rule" governing this behavior? Try another trial and see if your idea checks out...
Question 2.8
In the first two pages of this lesson, you studied the behavior of electrons on a single conductor and electrons on two separate conductors that can join. Summarize the rules or patterns you observed about electron behavior in conductors.
How do you think this behavior would be different in an insulator?
3. Insulators -- Charge Behavior
This set of questions uses a PhET simulation modeling charges in a balloon. Begin by playing with the simulation to figure out how everything works. Then click the reset button on the bottom right corner & begin the questions below!
Question 3.1
There are three objects on the simulation -- the sweater, the balloon, and the wall. Would you characterize those objects as conductors or insulators? Why?
How do you expect charge to behave/move as a result?
Question 3.2
As you play with the simulation, what do you notice is different in this simulation compared to the previous versions you used with conductors (aside from the fact that these objects are insulators)?
Question 3.3
Before moving anything (or click the orange reset button if you already have), what is the charge of each object?
Question 3.4
When you rub the balloon against the sweater, what happens? Why? What is the name for this process?
Question 3.5
Now bring the balloon near the wall. What happens macroscopically (big picture) between the wall and balloon? What happens microscopically (to individual charges)? Why does the balloon stick to the wall?
Question 3.6
In the space below, draw a properly labeled force diagram for the balloon, when it is stuck against the wall. What force prevents the balloon from falling to the floor?
Note: Draw your sketch in the sketchpad below
Question 3.7
If the balloon was positively charged instead of negatively as it is in the simulation, would it still stick to the wall? Explain how this situation would be possible in terms of charge behavior and movement.
