Overview
Introduction Purpose As you probably noticed from the electrostatics lab, sometimes it’s pretty hard to get precise, consistent charges that stay where you want them, so in this lab we will be using our computer to simulate chargesLinks to an external site.and their fields in order to gain a more intuitive understanding of Electric Fields. By the end of this lab you should be able to:
Materials/Equipment
Computer
Charges and Fields simulator
Electric Hockey simulator
Tips
You will need to use Excel to plot data.
Note: Arrange your data in excel, in x and y columns. Highlight the data and use Ctrl Q to bring up Quick Analysis. Go to Charts and Scatter. Click + to bring up Chart Elements, including Axis Titles, Trendline Options, and Equation.
More resources:
See this site for review of Charts in Excel.Links to an external site.
See this site for a Trend line in ExcelLinks to an external site..
Flag question: Question 1Question 11 pts
Field of a point charge Procedure: 1. Open Charges and FieldLinks to an external site. simulation https://phet.colorado.edu/en/simulations/charges-and-fieldsLinks to an external site. and click Run Now. 2. Once the simulation opens, check the boxes next to grid and values. 3. Place a 1 nC positive point charge in the middle of the screen. 4. Place a few electric field sensors around the charge.
Question:
The length of the arrow corresponds to the strength of the E-field. Where do you put the sensors to get the longest arrows?
Group of answer choicesCloser to the chargeFarther from the charge
The field is the same everywhere
Flag question: Question 2Question 24 pts
Field of a point charge, continued
Upload a sketch of the electric field in vector form for the +1 nC charge. Draw 12 evenly spaced arrows of the samle length, around the charge.
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Flag question: Question 3Question 32 pts
Field of a point charge, continued:
How would your sketch change if you used a negative charge? Make a prediction.
Test your prediction for the negative point charge using the simulation. (The reset is in the lower right hand corner)
Were you correct? Why or why not?
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Relationship between distance and electric field: Based only on your observations from the previous section, what would you guess the mathematical relationship is between the distance from a point charge and electric field strength?
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Relationship between distance and electric field:
Procedure:
Using the ruler tool and the electric fields sensors, find the electric field at 10 different distances from the point charge and enter them in a table.
Plot these points in excel and find the appropriate trendline. Make sure to label your axes and units and put the equation on the graph.
Upload a picture of your graph.
Upload Choose a File
Screenshot 2025-02-23 160532.png has been removed.
Flag question: Question 6Question 62 pts
Relationship between distance and electric field continued:
Based on your graph, what is the mathematical relationship between distance from a point charge and its electric field strength? Did you predict correctly?
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Relationship between charge and electric field strength:
Based only on your observations from the previous section, what would you guess the mathematical relationship is between charge and electric field strength?
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pspanspanspanspanspanspanView keyboard shortcutsAccessibility Checker1 wordSwitch to the html editorFullscreenFlag question: Question 8Question 84 pts
Relationship between charge and electric field strength:
Procedure
Using the ruler tool and an electric field sensor you leave in one place, find the electric field strength as you add more and more charges and enter your data in a table.
Plot these points in excel and find the appropriate trendline. Make sure to label your axes and units and put the equation on the graph.
Upload a picture of your graph.
Upload Choose a File
Flag question: Question 9Question 92 pts
Relationship between charge and electric field strength, continued:
Based on your graph, what is the mathematical relationship between charge and electric field strength? Did you predict correctly?
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Multiple Charges:
Predict the electric field vectors for two equal charges:
What pattern would you expect for the electric field produced by a pair of charges which are equal in size and have the same sign? (Do not set up the simulation until after you have made your prediction!) Draw your prediction of the electric field directional arrows you would expect. Show at least a dozen arrows at evenly spaced intervals covering the entire area of the box, including the area between the charges.
Take a picture of your sketch and upload it.
Upload Choose a File
Flag question: Question 11Question 112 pts
Multiple Charges, continued:
Check your prediction with the simulation:
In what ways is the pattern (pair of charges which are equal in size and have the same sign) similar to your prediction? In what ways is it different?
Where is the electric field the strongest? Where is it the weakest?
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Multiple Charges, continued:
Electric field vectors for two opposite charges:
Do the simulation for the electric field produced by a pair of charges which are equal in size but opposite in sign.
The electric field is the strongest:
Group of answer choicesFar from the chargesBetween the charges
Flag question: Question 13Question 131 pts
Multiple Charges, continued:
Electric field vectors for unequal charges:
Do the simulation for a +2 nC and -1 nC pair.
Compared to the +1 nC and -1 nC pair, how does this change the strength of the electric field between the charges?
Group of answer choicesIt increasesIt is zero
It decreases
It stays the same
Flag question: Question 14Question 142 pts
Conclusions
Based on your results (field of a point charge) and without looking it up, please guess a mathematical relationship (you do not need specific numbers or constants, just an approximate proportionality) between electric field, charge and distance from a charge. Justify your answer in a couple sentences.
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