1 Exam II vers 0001 Physics 1120 Fall 2007 NAME print please Student ID TA s Name Circle one Edwin Widjonarko Craig Hogle Mike Mullan Mike Hermele Naresh Sen Starting time of your Tues recitation write time in box 9am noon 1pm etc Please do not open the exam until you are told to Your exam should have 12 pages numbered 1 thru 12 This exam consists of 18 multiple choice questions worth 75 points total and two multipart long answer questions worth 25 points total Fill in the bubble sheet with a 2 pencil PLEASE follow all directions carefully if you don t we may not be able to identify your exam which would be a disaster for you Place a check in each box on the left as you complete the instructions Circle your TA s name above Print and bubble in your name on the bubble sheet Print and bubble in your student Identification Number Print and bubble in your Exam version 0001 or 0002 in the upper left of your bubble sheet in the area marked 1234 Erase mistakes as thoroughly as possible Ask for a fresh bubble sheet if you fear you cannot thoroughly erase mistakes After you begin be sure to neatly print your name and ID on the long answer question pages At the end of the exam check that you have filled in the first 18 questions on the bubble sheet with only one bubble filled in for each question I have read and followed the instructions above Signature Note 1eV electron Volt 1 6 10 19 J Charge of the electron e 1 6 10 19 C Ver 0001 2 NOTE In ALL questions please assume the electrical potential is defined to be zero at infinity unless otherwise explicitly stated 1 A small surface is completely enclosed by a larger surface The volume inside the first surface is V1 The volume between the first and the second surface is V2 The total outward flux through the inner surface is positive but the total outward flux through the outer surface is negative What is the sign of the total charge contained within the volume V2 A Positive B Zero C Negative D Impossible to tell V2 V1 2 Two uniformly charged rods are each bent into a quarter circle of radius R The left rod is positive with linear charge density 3 l The right right is negative with linear charge density l What is the electrical potential at the point A 3Q Q located at the center as shown R A A V k B V k R C V k D V k R E V k R Ver 0001 3 A uniformly charged rod with linear charge density is positioned vertically as shown so that the distance between its lower end and the origin is L Its height is H What is the potential at a point located on the y axis at a distance D from the origin A B C D 3 E Ver 0001 4 4 A charged rod with the positive charge Q uniformly distributed along its length is positioned as shown Is the potential VA at a point A L r L A VA kQ r B VA kQ r D VA kQ L E VA kQ L C kQ r VA kQ L The next three questions refer to the figure below 5 The figure on the right shows the equipotential lines of the electric field A proton at rest is placed at a point A Which direction will it start moving 4V 3V 2V A up B down C right D left E will remain at rest 1V 0V 1 V 6 At which point is the electric field the weakest 2 V A At the point A B At the point B C At the point C 4 V D It is equally strong at points B and C E It is equally strong at all three points 3 V 7 How much external work does it take to move the proton with constant velocity from the point B to C A 3 eV Ver 0001 B 6 eV C 3 eV D 6 eV E 1 6 10 19 eV 5 8 The circuit shown on the picture includes three identical capacitors each having capacitance C How does the charge Q1 on the plates of the capacitor 1 compare with the charge Q2 on the plates of the capacitor 2 1 A Q1 Q2 B Q1 Q2 C Q1 Q2 D Q1 Q2 E Q1 Q2 1 1 2 1 3 3 2 2 9 What is the effective capacitance of this circuit A C B 2C C 2C 3 D 3C 2 E 3C 10 A large parallel plate capacitor whose plates area is A and distance between the plates d is charged so that the charges on its plates are Q and Q Its plates are isolated A metal slab of thickness L is inserted between the plates as shown How would the electric field s strength at the point A change if the slab were removed A Increase B Decrease C Remain the same D Impossible to tell 11 How would the energy of the capacitor change if the slab were removed A Increase B Decrease C Remain the same D Impossible to tell 12 An electron is injected between the plates of a large parallel plate capacitor exactly in the middle with the initial kinetic energy KEi The distances between the plates is d the charges on the plates are Q and Q What is the final kinetic energy KEf of the electron as it hits one of the plates Ver 0001 6 A KEf KEi Q2 d 2 0 A B KEf KEi Q2 d 2 0 A C KEf KEi Q d e 2 0 A D KEf KEi Q d e 2 0 A F KEf KEi d e2 2 0 A 13 What is the potential at the center of the square shown on the figure Four charges are located at the corners of this square as shown A B C D E Ver 0001 7 14 A circuit consists of a battery and three resistors as shown The current through each of the resistors is I What is the current through the battery A I B 3I C 2I D 0 E I 15 Two charges Q and 2Q are arranged in the way shown What is the potential at the point A A 3Q r B 3Q 2r C Q r D 0 E 2Q r 16 The figure on the right shows field lines of the electric field Which one of the figures below shows correctly the equipotential lines of this electric field Ver 0001 8 A C B D E 17 A wire carries a current of 20A How many electrons pass through this wire in 1 minute A 7 5 1021 B 1 25 1020 C 20 1010 D 20 E 1 6 10 19 Ver 0001 9 18 Two resistors one is twice as long but only half as thick as the other its diameter is …
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