no tagsHomework002SteveSekula, 29 August 2010 (created 26 August 2010)Homework 2Expectations for the quality of your handed-in homework are available athttp://www.physics.smu.edu/sekula/phy1308/homework.pdf. Failure to meetthese guidelines will result in loss of points as detailed in that document.This assignment covers material from Wolfson Chapter 20.4-20.5, and21.1-21.3. Each problem is worth 20 points, and the total assignment isworth 80 points. You are not required to do the Bonus Exam PointsCompetition (it doesn't count against you to not participate, but it IS worthextra points on the first in-class exam if you come in 1st, 2nd, or 3rd place -see the rules below).This homework is due in my mailbox in Fondren Science 102 nolater than 5:00pm on Tuesday, September 7Reading Assignment:Chapter 20.4-20.5, Chapter 21.1-21.3Problems:Problem SS-4A dipole (see illustration below), with charges and and separation between the charges of , is located from another charge . The dipole moment vector isoriented perpendicular to the line between and the point halfwayGeneral Physics - E&M (PHY 1308) LectureNotesGeneral Physics - E&M (PHY 1308) LectureNotes+4:0 0 Â 1À8C À4:0 0 Â 1À8C5:0 0 Â 1À10m 40:0 0 Â 1À7mQ 20:0 0 = À Â 1À8CQ General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Documents/Notebooks/PHY1308...1 of 7 08/29/2010 04:38 PMbetween the ends of the dipole. Using this information,What is the net torque on the dipole?What is the net force on the dipole?What is the direction of the net force?Problem SS-5Phototubes are light detector devices that are critical components inmedical imaging technology (for instance, in combination with light-sensitive crystals in PET scanners. c.f. Johannes Czernin, Magnus Dahlbom,O. Ratib, and Christiaan Schiepers, "Atlas of PET/CT Imaging in Oncology",2004). A key part of the phototube is a "dynode" - a small, cup-shapedpiece of metal that is used to accelerate electrons (amplifying the signal)produced when photons strike the phototube.Consider such a cup, in two dimensions, as illustrated below. Treat it as aperfect semicircle of radius whose center is located at point . If the cupcarries a total electric charge of distributed uniformly over its length,determine the electric field at the point .Hints: treat the cup as a series of small units of charge, (see illustration),and write in terms of the small unit of angle subtended by the smallunit of charge. Then integrate over to obtain the net field at .a P Q E ~P dq dq dÒ dÒ P General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Documents/Notebooks/PHY1308...2 of 7 08/29/2010 04:38 PMProblem SS-6Determine the charges of each charge (labeled A, B, and C) in the drawingbelow. Determine the net charge.General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Documents/Notebooks/PHY1308...3 of 7 08/29/2010 04:38 PMProblem SS-7The tip of a scanning-tunneling electron microscope, a common tool forimaging the fine detail of viruses and other microscopic structures, can bedescribed as a right cone. That cone is a closed surface with a circular baseof radius , a height of length , and a hypotenuse of length (for eachright-triangle that makes up a vertical slice of the cone), as in theillustration below. Consider the case where this tip is immersed in auniform electric field, , parallel to the height-axis of the cone. Show thatthe flux through the tip is consistent with the prediction from Gauss's Law.Bonus Exam Points Competition: Electric Field Hockeyb h L E ~General Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Documents/Notebooks/PHY1308...4 of 7 08/29/2010 04:38 PMWelcome to your first bonus points competition. Your job is simple: get theelectrically charged puck in the game "Electric Field Hockey" (availablefrom http://phet.colorado.edu/en/simulation/electric-hockey) from itsstarting point to the goal in the shortest time possible, using as fewcharges as possible. Results must be submitted electronically (see below)by 5pm on Tuesday, Sept. 7. If you need access to a computer, let me know.Here are the rules:RulesYou must do this on Level 3 of the game (click the "Level 3" radiobutton at the bottom of the game)1.You must use the default puck settings (mass=25 and "puck ispositive"). Don't change any of these settings.2.You must put a movie of your performance up on YouTube and submitthe link to the video as proof of your accomplishment. The movie willtell me the time it took for the puck to go from start to goal. Tips onrecording the game are given below.3.You can work as a team or alone (see below)4.ScoringYour score will be a time. That time will be determined as follows: the timeGeneral Physics - E&M (PHY 1308) - Lecture Notes file:///home/sekula/Documents/Notebooks/PHY1308...5 of 7 08/29/2010 04:38 PMit takes to get to the goal, plus a 0.2 second time penalty for every electriccharge you place on the board. Shortest time, determined by this method,wins first place.Ranking and PointsThe shortest time gets 15 bonus points on the first in-class exam. Thesecond-shortest time gets 10 points. The third-shortest time gets 5 points.Working together is strongly encouraged, but incurs a sharing of points. Iftwo people work together, and they come in first place, they each get 66%of the points (0.66*15=10). If three people work together and come in firstplace, they each get 33% of the points (0.33*15=5). If four people worktogether, they each get 15% of the total. Etc. The fraction of points ishalved each time after the first team of two. Similarly for second and thirdplace.Recording the GameYou need to record the game and make a movie, which you can then uploadto YouTube. Here are programs that let you easily record such a movie ondifferent operating systems:Windows: CamStudio (http://camstudio.org/) - note, this records audiofrom your microphone, too, so if you don't want your voice in the moviemake sure to disable audio recording.Mac: Copernicus (http://www.danicsoft.com/software/copernicus/)Linux: "Record My Desktop" (http://recordmydesktop.sourceforge.net/about.php)I recommend you work on your layout of the charges for directing the puck.Once you have it setup the way you want, then click the "Reset" button onelast time, start recording your desktop, and click the "Start" button in thegame. Upload the video to YouTube, and then send me the link to the video.If you're having trouble getting
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