Theoretical BackgroundThe Coulomb's law describes the ...



Lab #3: Coulomb’s LawName: _________________________________________ Period: ___Physics 2018Due Date: _________________________________________________3057525446405d is the distance between the charged particles.q1 represents the quantity of charge of one particle.q2 is the quantity of charge of the other particle.k is the proportionality constant. 00d is the distance between the charged particles.q1 represents the quantity of charge of one particle.q2 is the quantity of charge of the other particle.k is the proportionality constant. INSTRUCTIONS: Follow the link on Schoology for Lab #3 in “Coulomb’s Law” folder. Complete each virtual experiment below before trying it out in the real world.161925048895Coulomb’s Law:320040013970k = 9,000,000,000 N·m2/C2 or 9.0 × 109 N·m2/C200k = 9,000,000,000 N·m2/C2 or 9.0 × 109 N·m2/C2Data Collection – Virtual LabExperiment #1:Set Up: Place the neutral “pith balls” approximately 10 units apart. Experiment by moving the neutral charges closer and farther apart. What happens? Why?Increase the charge on “Charge One” and repeat step #2. What happens? What did you expect to happen? If this was “real life” what would have happened and how do you know?Experiment #2:Set Up: Place the neutral “pith balls” approximately 10 units apart. Set the charge for “Charge One” by clicking the UP ARROW once. Repeat for “Charge Two” Record the charge for each, the distance, and the angle.Increase the charge on “Charge One” three times, record the angle for each increased charge.You should have 4 data points in total!Keep “Charge Two” the same!Experiment #3:Set Up: Place the neutral “pith balls” approximately 20 units apart. Set the charge for “Charge One” by clicking the UP ARROW once. Repeat for “Charge Two” Record the charge for each, the distance, and the angle.Increase the charge on “Charge One” three times, record the angle for each increased charge.You should have 4 data points in total!Keep “Charge Two” the same!Check for Understanding – In your notebookUse the equation for Coulomb’s Law to calculate the electrostatic force (Fe) for each of the eight scenarios from Experiment #2 and Experiment #3Draw one FBD for any data point in Experiment #2. Include numbers!Draw one FBD for any data point in Experiment #3. Include numbers!Compare your results today to your results from yesterday. How are they similar and different?Data Collection – Pith BallsMaterials: 2 Styrofoam (pith) balls on string; a plastic ruler; a meter stick; mass scale; a clear plastic rod and a piece of wool.Theoretical BackgroundThe Coulomb's law describes the interaction between point charges.276225055880000In an electroscope made by two pith balls, the Coulomb force can be determined by the mass of the pit ball and the distance between the balls. Fig. 1 below demonstrates the setup and the free- body diagram for the force analysis.Fig. 1 On the left is the schematics of the experimental setup. The strings should join at the origin of a protractor so that the angle q can be easily measured. On the right is the free-body diagram for analyzing the forces acting on a pith ball.When the pith balls are charged with equal amount of charge, q, they repel each other to a distance r (measured from the centers of the balls), due to a Coulomb force:This Coulomb force Fe is balanced by two other forces, the tension force T and the weight on the ball mg. From the free-body diagram, the relationship between Fe and mg can be determined by the angle ? or the ball-to-ball distance r without knowing T.This relationship allows us to estimate the amount of charge on the pith balls through measuring the angle ? or the ball-to-ball distance r:Procedure:Collect materials from Demo Table.Measure and record the mass of each pith ball w/ string.Have one group member hold the ends of each string so they hang evenly (like Fig. 1) away from your body.Rub the clear plastic rod with the wool to charge it. Make an electroscope out of tape (sticky tape lab) to determine the charge of the rod.Charge each pith ball by conduction using the rod. (It’s ok if the pith balls touch each other while being charged, just do not touch them with your hands or anything that could ground it.)Measure and record the distance r between the center of the balls using a ruler (wood or plastic, not one with a metal rod on it)Repeat 4-6 three times to obtain three different amounts of charge q.Observing Points:Does r change with time? If so, how fast? What does it mean? If not… why?How else could you charge the pith balls with the materials you have? Try it.Lab Analysis: Calculate the charge q on each ball from the measurement of r using Coulomb’s Law Conduct an error analysis. Determine sources of error in this experiment.NOTE: “Human error” is present all the time, this is NOT to be your main point! ................
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