2212_Test1_Key-1 - Problem 1(25 Points An electric quadrapole located at the origin consist of two identical permanent dipoles held perpendicular

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Unformatted text preview: Problem 1 (25 Points) An electric quadrapole located at the origin consist of two identical permanent dipoles held perpendicular to each other as indicated on the diagram below. Each dipole composed of a positive and negative charge q separated by a distance 3. A .5) (a 6pts) On the diagram below draw , E) 5 and label the net electric field vec- E 1?: tors due to the quadrapole at locations .0 A A and B , a distance d from the ori— gin on the y and x axis respectively. (recall that longer arrows mean larger _q magnitudes) FQ 2' E25 ' - - i vq EEG} u ,t La ’Dl‘oole 1 (Grind-(19 «log \ \l/. E X’ayis) {q} d us Dipole 1 (minded «lowj s 3 — me :5) L—4 (b 13pts) A negative charge —Q is placed at location A. What is the magnitude and direction of the net force actingbon this charge due to the dipole? You can assume that d >> ‘14 _\__ S r .. E g + : E 4» E” Em“: (“WC—o a? 101°) nu ' a Mk N» IA 2:4 A ‘ 13$ : O ‘ -" q I 3’5 > Em < ’ “6° 23””) g : ‘ H < II 2I O NH 2—3 “Cl-$1 fDlmcl'iou—ls opeosik 5.1+ in alcove ‘ijt- —» a 4.3635 7L7” ’QELML : 4TTéo 013 «’2’0» U quadrwl t (c 6pts) Does the negative charge —Q cause the d-ipele to rotate clockwise, counterclockwise or not at all. Please provide justification for your answer. Drawing a figure may help. Covtfiider Jlru. {was «C‘l’iVj 0k «HM. (Ivadl’u‘aak’a Salk/(dud clumlqs W0" 6 Two ck" <5 ow 341W: Jon} a‘o‘a‘eaw +0 ’ ‘ MAC («Hind mh'l'iau, been“, m mo é“, es 0“ M x,a,¢{5 Jemms‘l'fle-l-e, Problem 2 (25 Points) You have two strips of invisible tape, each about 15 cm long, with a mass of about 0.20 g. You smooth them down onto a table, one on top of the other, as was done in lecture and lab. You label the top tape “A” and the lower tape “B” The “sandwic ” of two tapes is pulled slowly off the table. You rub your hand along the slick side of the upper tape, and observe that the tapes7 still stuck together, do not interact with your hand. Now you quickly pull the tapes apart. You observe that both tape “A” and tape “B” are attracted to your hand, and the tapes are attracted to each other. Tape “B” is repelled by a negatively charged plastic pen. ,_————-———_—————-——————- original position of tape B You attach the ends of tape “B” to the tops of two books, so it hangs loosely, in the position shown by the dotted line. You hold tape “A” above it, and slowly bring it down above tape “B”. When tape “A” is 2.3 cm above tape “B”, you see the middle of tape “B” begin to buckle upwards, as shown in the diagram. (a 20pts) Calculate approximately the amount of charge on tape “B”, both magnitude and sign. Start from a fundamental principle and clearly show all steps in your work. TA??- 3 is MjodinJ 0km,qu . ' I W we? is sust wk we We vii/ugh“ 34,: Ml ‘QM‘C‘C on 50 [001k 3 SP 1 ' ‘ 44M c‘l’iom f$ 4‘70 u4l— We. SAW site?“ eknd M ’ W»? (W). M Emma—'2‘ 015 «He—L flaw) Eflm . g at ’v C ': E? *W ‘;7 7% ~ 52' (Mk «(JeromeL M) 22. b m7 also lqu 7')?be : l) ’k ,— :M c 41756” (0.7..(o'5)(‘i-3)(2.zum’2 ’/ ' «‘3, 3 Z 3 Z =(» j z ' [10740 C (b 5pts) What approximation(s) or assumptions did you make in this calculation? Explain clearly. (We 06.1.1“. «kl/tod- qud—c. dupe. \‘s sus‘nmdefl waif? jug— aei‘x 0-9 i’l' alloweol “9 +7, “be ’ VJL acemylMd-al. JAMI- (WvAu-CJ- \vj luff, A as q Problem 3 (25 Points) (a. 3pts) A dipole consisting of two op— positely charged balls with charge +q C and —q connected by a wooden stick of length 3 is located as shown to the right. On the diagram draw an arrow representing the electric field at loca- tion C, due to the dipole. Label this arrow Ed. (b 3pts) Now a neutral solid plastic sphere is placed at the location indicated, On the diagram7 show the distribution of charges in and /or on the plastic sphere, using the diagrammatic conventions discussed in the textbook and in class. ’3» QM ’ C GE plastic sphere (c 4pts) At location C in the diagram above, draw and label two arrows (recall that longer arrows mean larger magnitudes): 1. Ed, the electric field due only to the dipole 2. Ep, the electric field due only to the neutral plastic sphere. flail 2’ El (d 3pts) How does the magnitude of Ed in part (0) compare to the magnitude of Ed in part (a) at location C? Circle the appropriate description: greater smaller impossible to tell (e 3pts) Now the plastic sphere is replaced by a solid neutral metal sphere. On the diagram below, show the distribution of charges in and/ or on the solid metal sphere using the diagrammatic conventions discussed in the textbook and in class. X C 699 metal \ sphere \ \ \ ‘ (f 3pts) On the diagram above at location D, draw an arrow representing the electric field due to the dipole and label this vector Ed. (g 6pts) Location D is a distance L from the dipole. What is the magnitude of the electric field at location D due to the polarization of the metal sphere? Location D is on the perpendicular axis of the dipole. ———v "E: ; Lug Jae-k, meskciu‘l’iou of— Cvo“ cs OKMMGQ (A A f? O stume. D ' ._..v A ,_._ 4: ~ bleQD- \ t: \Ed\’_ L D (3 Problem 4 (25 Points) The following program is intended to calculate the electric field at several locations due to two particles. a proton and an alpha particle (a helium nucleus: two protons and two neutrons). Complete the program by filling in blanks and writing VPython code in indicated locations. You will not be penalized for errors in VPython syntax, but you must get the physics and math, including vectors, correct. You may find it helpful to write out the algebra, then translate it to VPython. from Visual import * # constants oofpez = 9e9 protonq = 1.6e—19 alphaq = 2*protonq scalefactor = 1e—16 ## assume this is reasonable # objects proton = sphere(pos = vector(0, 0, 1e—9), radius = 1e—10, color = color.cyan) alpha = sphere(pos = vector(—2e—9, -3e—9, 0), radius = 2e—10, color=color.green) obslist = [vector(5e—9, 59—9, 5e-9), vector(-5e—9, -5e—9, —5e—9), vector(Se-9, —Se—9, -5e-9)] for obs in obslist: ##(a 9pts) Write code necessary to get E due to the proton, at this location: (‘P :: obs -- Pro'l'bvt.(>oc (pmac Max:109) ((3ka '= '9 59 —; oofrpea’fiarol-omb /rf>wx5“i ¥ rekocl' ##(b 9pts) Write code necessary to get 5 due to the alpha, at this location: TA 1 Obs — alpha?“ («Mus-’— Masha) ("AW-V :— (a [raw/tag, Em c oocfeeu «\(Jlfgmcg /NLMA3W2 “Prod/lac? ##(c 3pts) Write code necessary to get Ema, at this location: Emfi’ ’5 E7P + Eek ##(d 4pts) Create an arrow to display End at this location: arrow(pos= b5 , axis: ) ...
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This note was uploaded on 05/23/2011 for the course PHYISCS 2212 taught by Professor Shatz during the Spring '10 term at Georgia Institute of Technology.

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2212_Test1_Key-1 - Problem 1(25 Points An electric quadrapole located at the origin consist of two identical permanent dipoles held perpendicular

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