Purpose: Develop an understanding of the electric field concept, and it's representation using field lines. Relate the electric field via simulation the electric force due to a given source charge amount, for various amounts of test charge. Apparatus: Use the simulation here : https://phet.colorado.edu/sims/html/coulombs-law/latest/coulombs-law_en.html Include a screenshot (not a photo of your screen!) of the simulation in action, as it appeared while you were taking data. One representative image is plenty, you needn't show the apparatus for each individual data point. Directions: Using the simulation (atomic scale), first record the value of the (positive) source charge. The source charge, for our purposes, will be the amount of charge at the position 0 pm. This amount of source charge will be a control for the duration of the experiment / simulation. Now, choose one position where you will place the test charge. It could be any measurable distance away. Record the distance. Now, record the force on the test charge by the source charge. Vary the amount of test charge by changing the slider for charge 2, recording the value of the force on the test charge each time. Record both the test charge magnitude and the force magnitude for each new test charge value in a data table. Use values for charge 2 {test charge} from 0 to + 10 e. Note that e is the elementary charge, whose magnitude is the same as the magnitude of the electron charge, 1.602 × 10 −19 C. Draw a single, representative, force diagram to represent the force on the test charge, by the source charge. Record the data in a table, and enter into Excel. Make note of the sign of each charge, and whether the force is attractive or repulsive. In writing the procedure section, make note of which is the dependent, and which is the independent variable in this experiment. Data Evaluation: • • • Plot the force in Newtons on the vertical axis, and the test charge magnitude, in Coulombs on the horizontal axis. What relationship does the data suggest? If you said 'linear', you're right! Be sure to include the units on both the vertical and horizontal axes. Use excel to plot a straight line of best fit for your data. Write the equation of best fit for this line, using the variables you have plotted. If you use y & x when you write this equation, you will lose points, and more importantly, you will miss point. DO NOT USE Y & X! Do not use y or x in the equation of best fit! Use the physics variables! DO NOT USE Y & X!! What are the units of the slope in the equation of the line that you have just written? What is the value of the slope? It's probably necessary to click on the 'format trend line label' and choose scientific notation. Symbolically, write the expression for Coulomb's law, this time with q1 & q2 replaced by q source and Qtest. Factor out Qtest and divide both sides by q test. This quotient F / Q test is in general the meaning of the electric field strength. In this case the source of the electric field was the source charge (point source). Using the values you've recorded earlier, calculate the % difference between F / Qtest and the slope of the line. This difference should be small. What does the slope of the line represent ? Describe qualitatively the relationship between the amount of test charge and the magnitude of the force.