no tagsHomework000SteveSekula, 18 January 2011 (created 17 January 2011)Expectations for the quality of your handed-in homework areavailable at http://www.physics.smu.edu/sekula/phy1308/homework.pdf. Failure to meet these guidelines will result in loss of pointsas detailed in that document. This assignment covers material from WolfsonChapter 20. Each problem is worth 20 points, and the total assignment isworth 100 points.This homework is due no later than 8:00pm on Monday, January 24.Reading Assignment:Appendix A, Chapter 20 (All)Exercise SS-1: Electric Charge and the Behavior of ElectricChargesFor this exercise, you will be using a computer simulation of electriccharges called "Electric Field of Dreams." It is free and available onlinefrom:http://phet.colorado.edu/en/simulation/efieldYou will need to use a computer with Java installed:Install Java:Windows and Linux: if it's not already installed,Select the "JRE" (Java Runtime Environment) link fromhttp://www.oracle.com/technetwork/java/javase/downloads/index.html or . . .General Physics - E&M (PHY 1308) LectureNotesGeneral Physics - E&M (PHY 1308) LectureNotesGeneral Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Dropbox/Documents/Notebook...1 of 6 01/18/2011 01:00 PMGo to this link: http://bit.ly/enbwQiFor Mac users: Java should already be installed if you are usingMax OSX Leopard or Snow Leopard.If you do not have access to a computer with Java and/or cannot installJava, please come to the office hours for help.InformationYou will be placing single electric charges, and pairs of electric charges,on a board. Arrows will appear around the charges, representing a "field offorce" around a charge. These arrows can be interpreted as follows (youwill explore this below): they indicate the direction of force exerted by thecharge as if it were acting on a tiny, almost negligible positive electriccharge placed on the board at the location of the arrow's tail. For instance,if you place a charge on the board and one of the arrows that results ispointing to the right, you can interpret this to mean that this is thedirection your charge would push on a tiny, tiny second positive chargeplaced on that location. The length of the arrow indicates the strength ofthe force at that location; longer arrows mean a stronger force. Thedirection of the arrow indicates the direction of the force.ProceduresProcedure:Create, observe and draw the electric field around a single negativepoint charge. To do this:Click on the "Properties" button and set the charge to -1.0Coulomb. Click the "Done" button on the properties window to saveyour changes.Click the "Add" button. This will add a -1.0 Coulomb (negative)charge to the simulation.You may move the charge around the field by dragging it with yourmouse pointer.The arrows indicate the direction of the force field around thecharge.Note that the arrows all point towards the charge with the largestarrows nearest the charge.In your Results section (see below) draw the charge and the fieldaround it.When you are done with this part of the exercise, clear thesimulation’s field by clicking the "Reset All" button and choosing1.General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Dropbox/Documents/Notebook...2 of 6 01/18/2011 01:00 PMyes.Create, observe and draw the electric field around a single positivepoint charge. To do this:Click on the "Properties" button and set the charge to +1.0Coulomb. Click the "Done" button on the properties window to saveyour changes.As above, click the "Add" button to create a single charge on theboard.Then click the "Properties" button and change the -1.0 Coulombcharge to a +1.0 Coulomb charge.Note the difference in direction of the arrows around this charge.In your Results section, draw the charge and the field around it.When done hit the "Reset All" button and choose yes to clear thesimulation’s field.2.Create, observe, and draw the electric field around two positivecharges. Do this by:Clicking on the "Properties" button and setting the charge to +1.0Coulomb. Click the "Done" button on the properties window to saveyour changes.Clicking the "Add" button twice in succession.Two charges should start to move around the screen with the fieldlines (arrows) indicating the direction and magnitude of theelectric force at each point in space.Hit the pause button to stop the charge movement and drag thecharges to opposite sides of the board.Draw a picture of the charges and the field between them in yourResults section.These are two of the same charge and thus their fields repel oneanother. You can therefore expect the field to be weakest betweenthe charges and greatest outside the charges where both fields arepushing the same way.Reset the simulation by hitting the "Reset All" button and sayingyes to the reset all.3.Create, observe, and draw the electric field around two opposite pointcharges. To do this:Click the "Properties" button and set the charge to -1.0 Coulomb.Click the "Done" button in the properties window to save yourchanges.Click the "Add" button once to give you a negative charge on theboard.Click the "Propeties" button again and change the charge to +1.04.General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Dropbox/Documents/Notebook...3 of 6 01/18/2011 01:00 PMCoulomb. Click the "Done" button in the properties window to saveyour changes.Click the "Add" button again, this time placing a positive electriccharge on the board.Now click the "Properties" button -and change the charge back to-1 Coulomb.The two charges should move around the screen, somewhatattracted to one another.Hit the pause button and use your cursor to drag the positivecharge to the right side of the screen and the negative charge tothe left side of the screen.Draw the charges and the field between them. Record the drawingin your Results sectionThe strongest field should be between the charges as they both arepulling in the same direction at this location.Reset the simulation by hitting the "Reset all " button and choosingyes for the question.Create, observe, and comment on the behavior of a tiny electric chargein the present of a bigger electric charge. To do this:Click the "Properties" button and set the charge to +10.0 Coulomb.Set the mass to 100.0. Click the "Done" button in the propertieswindow to save your changes.Click the "Add" button once to give you a negative charge on theboard.Click the "Propeties" button again and change the charge to+0.001
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