Activity 8
1. "Exploring Electric Charges" by Dorina Kosztin
Simulation: Balloons and Static Electricity
Exploring electric charges
PURPOSE: Use simulations to explore electrostatic interactions
In this online lab you will use simulations to check your
knowledge regarding electrostatic interactions.
Balloons and Static Electricity Simulation
To interactively explore some of the concepts you have
learned so far please go to the Physics
Education Technology Web site (http://phet.colorado.edu/en/simulations/category/new).
We will start with the Balloons
and Static Electricity simulation, found under Physics -> Electricity,
Magnets and Circuits.
The simulation “Balloons and Static Electricity” can be
run online (chose “Run now”) or downloaded and runs on your own computer
(choose “Download”).
Once your application has started, click “Reset All”.
Make sure that only the “show all
charges” and “wall” buttons are
selected.
1)
Look at the balloon. What can you say about its
charge? (Hint: count both types of charges)
The balloon’s
charge is equal with 4 positive charges and 4 negative charges.
2)
Click and drag the balloon and rub it against
the sweater. What happens to the balloon?
The balloon collected
all of the sweater’s negative charges and is now attracted to the sweater.
3)
How did the balloon get charged, with what type
of charge?
The balloon got
charged because the valence electrons of an atom are free to combine with any
accepting molecules. It collected a negative charge.
4)
Where did that charge come from?
The charge came
from the electrons of the atoms on the sweater.
5)
What happened to the sweater? How did it get
charged?
The sweater lost
all of its electrons and now only has protons, so it has a positive charge.
6)
Bring the balloon in the middle, between the sweater
and the wall. What happens to the balloon when you let it go? Explain.
The balloon is
attracted to the sweater. Since electrons and protons are attracted to each
other, the positively charged sweater and the negatively charged balloon are
attracted.
7)
What is the overall charge of the wall?
The overall charge
of the wall is neutral. It has an equal amount of positive and negative
charges.
8)
What do you think will happen when the balloon
is brought close to the wall? Predict first.
The balloon will collect the negative charges from the wall.
9)
Bring the balloon in contact with the wall. What
happens to the charges in the wall?
The negative
charges in the wall actually move away from the balloon.
10)
Let go of the balloon. What happens? Explain.
The balloon stays against the wall. The balloon is attracted to the wall because the positive charges are attracted to the negative charges in the balloon.
11)
Click the “Reset All” button. Select “show all
charges”, and “Two balloons”. What can you tell about the overall charge of all
the objects in your simulation window?
All of the objects have a neutral charge with an equal number of positive and negative charges.
12)
Select “Show charge differences”. Rub each
balloon against the sweater. What happens to each one of them?
Both of the balloons collect negative charges and attract to the
sweater.
13)
Why are the two balloons stuck on the sweater?
The two balloons
are stuck on the sweater because the negative charges picked up from the
sweater create an attraction between the positively charged sweater and the
negatively charged balloons.
14)
Try to get one balloon off the sweater by using
the other balloon. Can you do it? If yes, explain why this is possible.
Yes, I put one balloon between the sweater and pushed the other balloon
away. This made the negative charges in the pushed balloon repel from the
negative charges in the moved balloon.
Go back to your web browser window and from the
simulations under Physics -> Electricity, Magnets and Circuits, select “John
Travoltage”.
1) Predict
what will happen to John if he rubs his foot against the carpet.
I think that the
negative charges in the floor will conduct into John.
2) Rub John’s foot on the carpet by clicking and dragging his foot few times. What happens?
Negative charges
flow into and throughout John’s body.
3) Predict what will happen if John touches the door knob.
I think that the
negative charges in his body will go into the doorknob and into the ground.
4) Click
and drag John’s hand such that it touched the doorknob. What happened?
The negative
charges flowed from John’s body into the doorknob through a stream of
electricity.
5) What
would you call what happened to John?
I would call it a
static discharge, similar to a lightning bolt but on a much smaller scale.
6) How
is this different from the balloon and sweater or balloon and wall touching
each other?
This is different because the negative charges
didn’t just transfer from item to item. They transferred from a body to a metal
object and into the ground.
2. Original teaching idea for a chemistry subject
Name: __________________
Date:___________
Exploring Concentration
To begin this simulation, go online to http://phet.colorado.edu/en/simulation/concentration. The chemistry simulation is called “Concentration”. Click on Run Now! to begin the activity. Follow the directions and answer the following questions.
1. Before starting the simulation,
define concentration in your own words.
2. Select “solid” and add any solute
into the water by dragging the shaker. What do you notice as you add more of
the solute into the water? What does this tell you about the concentration of
the mix?
3. Now click the refresh arrow on the
bottom right. Drag the end of the concentration box into the bottom of the water
tank. The connected box should say 0.000. Add enough of the solute called drink
mix so that the concentration reads around 2 mol/L. Next, add more water to the
mix by pulling the upper drain to the right. Describe what happens to the concentration.
4. Pull the bottom drain and observe
what happens to the concentration. Explain the difference between adding to and
taking away from the mix.
5. Keep adding solid drink mix into the
solution until the water is fully saturated. At what concentration does the
drink mix become saturated? Describe what saturated means.
6. Select “solution” instead of solid
and squeeze some drink mix into the water. What is different when you add
solution instead of solid?
7. Give at least 2 examples of common
products for both a liquid solution and a solid solute.
Science Standards Grade 12
- G.12.1 - Identify personal interests in science and technology, implications that these interests might have for future education, and decisions to be considered.
- A.12.5 - Show how the ideas and themes of science can be used to make real-life decisions about careers, work places, life-styles, and use of resources.
- B. 12.3 - Relate the major themes of science to human progress in understanding science and the world
- B.12.4 - Show how basic research and applied research contribute to new discoveries, inventions, and applications.
