21 Solved Questions on General Physics II - Midterm Exam | PHYS 1120, Exams of Physics

Download 21 Solved Questions on General Physics II - Midterm Exam | PHYS 1120 and more Exams Physics in PDF only on Docsity! 5, cfs 5 1 Exam IT, vers. 0001 - Physics 1120 - Fall, 2011 NAME (print please) Student ID # TA’s Name(Cirele one!): Jorge Hernandez-Charpak, Jack Houlton, Scott Johnson, Zhao Kang, Andrew Koller, Vasily Kravtsov, Galan Moody, Brian Neyenbuis Starting time of your Tues recitation (write time in box: 9am, noon, Ipm, etc) Please do not open the exam until you are told to. Your exam should have 8 pages, numbered 1 thru 8. This exam consists of 21 multiple-choice questions. We will drop one wrong answer, so you will be graded on 20 questions, at 5 points each, for a total of 100 points. 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. L Circle your TA's name. Print and bubble m 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. Please leave the areas labeled Code and Date blank Erase mistakes as thoroughly as possible. Ask for a fresh bubble sheet if you fear you cannot thoroughly erase mistakes. U UU UOG As you take the exam, circle the correct answers on your exam as well as mark them on the bubble sheet, so we can grade the exam, if your bubble sheet is lost. At the end of the exam, check that you have filled in the first 21 questions on the bubble sheet, with only one bubble filled in for each question. U Ihave read and followed the instructions above. Signature Possibly useful information: @=16x10C, c5 = 8.85 x 10°12 C2 /N mm’, k= 1/(4ee,) = 9.0 x10? Nm? / C2 Vers.0001 +4 1. Three point charges are located at the comers of a a square as shown. What is the voltage at the fourth comer of the square? Assume V=0 at infinity. Ko #0 Kov2 3k ke k HONE yy HO GMO py HE py —He a a av2 +kQ | -kQ , RQ Ve SF of A) 2. A capacitor has a voltage VY across its plates. An electron, initially at rest, is released from a point very close to the negative plate of a capacitor and it accelerates toward the positive plate. The initial condition is shown in the diagram. The electron has charge g =-¢ and mass #. There is no gravity in this problem. What is the final speed of the electron just before it collides with the positive plate? ye OFZ oly D) meV E) None of these. Ve kwy% > ve (2 3. A spherical insulating ball with radius R has a total charge Q distributed unifommly throughout the volume of the ball. What is the magnitude of the electric field at a distance 2R from the center of the sphere? a , . : : 4nr3 i [Possibly useful information: Volume of a sphere = t Surface area of a sphere = 4rr?] | ‘ 4 1 @ 1 @ . (A) Z ‘B) ———, — {A) Zero ( 4m R? © ATE 4R3 (Dine tat (E) none of these & & dn = Dna, FY, tary? = %, | 6 C= tag, 8 Vers.0001 The next two questions refer to this situation: This circuit has three identical light bulbs (labeled A, B, C). The battery and wires are all ideal. Vv 11. Rank the 3 bulbs, A, B, C, from brightest to dimmest (aya>s =C Se Careents B) B=CrA (C) A=B=C in diagram, (DJ) A>B>C ‘ (E) Cannot be determined le @|e 12. If bulb C burns out (a burnt out bulb has infinite resistance), what happens to the brightness . ¢ ce cute It gets dimmer, but is not completely dark is Tt goes completely dark (no current through it) (D)There is no change Vv A (E) Cannot be determined 8 [More specifi cy : ofbulbA?) Now babe : bbl esis tance ares np L decreaslS Cintiel = Rt Vo ~ 3, Renal =o 13. Two cylindrically shaped resistors labeled 1 and 2 are made of copper. The diameter of Resistor | is Dj, the diameter of Resistor 2 is Do, the length of Resistor 1 is L), and the length of Resistor 2 is Lz. Resistor 2 is twicc as long and one-half the diameter of resistor 1. That is, Lz = 2 L, and D2 = (1/2) D,. What is the ratio R>/Ry? (A) 1/2 @)1 (C2 m4 (E)s 4 resistor 2 Pf) sie) QS) f<1> ts Re eo R~ Ce a Vers.0001 ——-_ = 2% ~ 3K, Aly 14. A proton is in the vicinity of some charges (not shown) and is moved from its initial position (i) to its final position (#) by an external agent, along the dashed path shown. The solid lines are equipotentials. You may assume that before and after the move the proton is at rest. What work did the external agent do? [Please think carefully about the signs.] ‘A)-7.5 eV = ® TS bey ~ A lA (C)-2.5 eV =g AV Bs abe) = e(- jasv-(-15v)) = O.5eV 15. In three different regions of space (labeled 1, IL, and INN), the electric fields are accurately indicated by the clectric ficld lines shown. The distance from point A to point B is the same in all three regions. In which region is the magnitude of the voltage difference [AV ie the smallest? _—_ _—— ————_ —_—_,_ _—_ ~A__B AB ss e ¢ — yes a a ___ _—__ Y Fspulet 0 m1 an (vreiont B)region I = C) region UL |AVag] = JE. Ar} D) the voltage difference in regions I and III tie for smallest > E) none of these. ir Same i all COS PS 16. A large Van de Graaff generator (a metal sphere that builds up charge) has radius R=2 m and builds up a charge of 100 C. What is the voltage at the surface of the sphere? Assume V=0 at infinity. [1 kV=10° V] R@p= 4x4 Nntfc® KOO / 5p Oeow B)225kV C)900KV D)zero = 4SKIooV E-field onside spite Cage dish: bahon Sant ss bhatot pom? thera @O cene- Vers.0001 > fe ree een kan The next two problems refer to the following situation: Two capacitors are attached in series to an ideal battery. (Before the capacitors were connected, there was no charge on any of the capacitor plates. Now, they have been connected for a long time.) The charge on the top plate of capacitor C; is +Q and on the bottom plate the charge is-Q. The capacitance of C2 is twice as large as the capacitance of C; (C2=2 C,). [Note the capacitor symbois are schematic, ic. the plate sizcs and gaps are not drawn ta scale.] C a” Cpuctta is ta SritS Carr 7 C, +g the Same chara -Q 17. What is the charge on the top plate of C2? > Sole un y I A) -Q G2 C)+Q/2 D)+2Q_ E)-O/2 V, 4 % y = pov Sh O QCV,2GVa + V,tVe=/OV Weeg 2 Q=62%.6 ®_ 18. What is the value of Q if C}=1 pF and V=10 V? [Remember C.=? C).] A) 10 uC B)33 nC (©R7 uC D)20 uc Son @) (= Ceres V Cotes = a = at. = O6 lu Q= QO ZMENOY = Bae 19. A particle with charge +q travels in the static electric field created by a single point particle +Q. It moves along the path shown in the diagram from A to B. Points A and B both are equal distances from the charge +Q. The work done by the electric field is: A) Positive B) Negative (Quer D) Not enough information to tell Dashed ling is eg, ipo tenbal we en Di=-W Vers.0001