Understanding the E vs. r relationship 3. for a variety of charge distributions Objectives: Empirically determine the E vs. r relationship for a variety of charge configurations including a point charge and a dipole. Compare/contrast the E vs. r relationship for a variety of charge configurations. Procedure: Open Charges and Field simulation http://phet.colorado.edu/simulations/sims.php? sim Charges_and Fields and click "Run Now". Place a 1 nC ( nano Coulomb) positive charge and E-Field sensor in the test area. Click "Show E-Field" to observe the field lines in the E-field. Observe the sensor's arrow as you drag it around the in the field. The sensor's arrow illustrates the force of attraction or repulsion at a point in an electric field. . Replace the positive charge with a negative charge. To remove charges, drag them back into their box. Click on show numbers and tape measure to measure the distances from a field-creating charge to a test charge. The tape measure can be dragged to a specific distance and placed anywhere on the field. Determine the E vs. r relationship for the following charge configurations. This means taking data from the simulation, making a graph and finding the best-fit curve. Use Microsoft Excel to draw graphs and use algebraic fit. Show equation on the graph. Make a one page word document containing all the graphs and save it to your thumb drive. Attach the printed one page word document to the Activity Scenario 1: Near a single negative charge Sketch of Scenario 1 (not the r (m) E (V/m or N/C) graph) Scenario 2: Above the center of a horizontal line of 11 positive charges Sketch of Scenario 2 r (m E (V/m or N/C) 1 Source: http:/phet.colorado.edu/en/simulation/charges-and-fields/teachingideasScenario 3: To the right of a negative and positive charge placed right next to each other on a horizontal line. (Center the charges on a grid intersection) Sketch 0f Scenario 3 1' (m) E (Wm or NEG) Scenario 4: Above a negative and positive charge placed 0.5 m apart on a . horizontal line (Center the charges on a grid intersection) Sketch 0f Scenano 4 1' {m} E (Vim or NEG) Discussion questions: You need to write your own answer after a group discussion for each of the following questions. 1. Is the E vs. r relationship the same (or similar] for different charge congurations? 2. Which congurations had similar E vs. r relationships? 3. Which had different E vs. r relationships? 4. According to Coulomb's Law, F o: lfrz. Why isn't E a lfr2 in each of the congurations you tested? Explain your answer qualitatively. Give an example. 2 PHET Electric Field graphs ~ 1 of 2 - + Automatic Zoom View as Text Downloa Single negative charge 11 + charges 400 0.2 201.4 0.2 375.5 0.4 61.5 0.4 169.4 350 -f(x) 0.6 26.4 0.6 87.7 300 0.8 14.2 0.8 76.9 250 1 9.2 1 56.8 1.2 6.3 1.2 43.6 200 250 150 100 200 161.4 9.33631561402141 x^-1.95205867968597 50 0 150 0 0 Column B 100 Power (Column B) 61.5 50 26.4 14.29.2 6.3 0 0.2 0.4 0.6 0.8 1 1.2 1.4 dipole together 0.2 174.5 200 0.4 34.1 180 f(x)=2.79330080714733 x^-2.62254331686977 0.6 11.4 160 0.8 5 140 1 2.8 120 1.2 1.6 100 Column B 80 Power (Column B) 60 40 20 0 - 0 0.2 0.4 0.6 0.8 1 1.2 1.4=54.9384424050011 x^-1.18746042635204 Column I Power (Column I) 2 0.4 0.6 0.8 1 1.2 1.4 dipole 0.5 appart 0.2 144 160 f(x) = 4.43700371714255 x^-2.28890270480748 0.4 45.2 140 0.6 16.8 0.8 7.8 120 1 4.1 100 1.2 2.5 80 . Column M Power (Column M) 60 40 20 0 - 0 0.2 0.4 0.6 0.8 1 1.2 1.4