31111 31111PHYSICS DEPARTMENTPHY 2054 Practice Exam #1 September 20, 2001B. WhitingName (print): Signature:On my honor, I have neither given nor received unauthorized aid on this examination.YOUR TEST NUMBER IS THE 5-DIGIT NUMBER AT THE TOP OF EACH PAGE.DIRECTIONS(1) Code your test number on your green answer sheet (use 76–80 for the 5-digit number). Code your nameon your answer sheet. Darken circles completely (errors can occur if too light). Code your student numberon your answer sheet.(2) Print your name on this sheet and sign it also.(3) Do all scratch work anywhere on this exam that you like. At the end of the test, this exam printout is to be turnedin. No credit will be given without both answer sheet and printout with scratch work most questions demand.(4) Work the questions in any order. Incorrect answers are not taken into account in any way; you may guess at answersyou don’t know if you feel that a correct answer is listed. Guessing on all questions will most likely result in failure.(5) If none of the answers is correct, please leave the answer sheet blank. It is not our intention to omit the right answer,but in case of a mistake, please leave the answer sheet blank.(6) Blacken the circle of your intended answer completely, using a number 2 pencil. Do not make any straymarks or the answer sheet may not read properly.(7) As an aid to the examiner (and yourself), in case of poorly marked answer sheets, please circle your selected answeron the examination sheet.(6) Good luck!!!>>>>>>>>WHEN YOU FINISH <<<<<<<<Hand in the green answer sheet separately.Constantsk = 1/(4π0) = 9.0 × 109N m2/C20= 8.85 × 10−12C2/( N m2) e = 1.6 × 10−19C1µC = 10−6C g = 9.8 m/s2electron mass: me= 9.11 × 10−31kg proton mass: mp= 1.67 × 10−27kgAvogadro’s number: 6.023 × 1023Atomic mass of Al = 27 g1. A parallel plate capacitor with a dielectric material (κ) between its plate is connected to a battery and charged to avoltage V and charge Q. The battery is then disconnected from the capacitor and the dielectric material is removed.Which of the following statements is true?(1) The voltage across the capacitor is constant; the charge decreases.(2) The voltage across the capacitor increases; the charge is constant.(3) The voltage across the capacitor is constant; the charge is constant.(4) The voltage across the capacitor decreases; the charge is constant.(5) The voltage across the capacitor is constant; the charge increases.2. A 9V battery is connected across two series-connected capacitors, C1=50µF and C2= 100µF (see figure). What voltage (in V) would berequired to separately charge a third capacitor, C3= 200µF, so that itwould have the same stored energy as C1? (Select the closest answer.)C1C29 VC3? V(1) 4.5 (2) 1.5 (3) 3.75 (4) 12 (5) 331111 311113. Which statement is false?(1) The electric potential energy difference in going from point A to point B is independent of the path taken.(2) At equilibrium, any excess charge on a conductor resides on the surface.(3) The electric field obeys the principle of superposition.(4) Negative charges are sources of electric field lines, while positive charges are sinks of electric field lines.(5) The electric force is a conservative force.4. An aluminum wire with a cross-sectional area of 4.0 × 10−6m2carries a current of 5.0 A. Find the drift speed of theelectrons in the wire. The density of aluminum is 2.7 g/cm3. (Assume that one electron is supplied by each atom.)(1) 0.77 km/s (2) 7.7 m/s (3) 19 km/s (4) 0.13 mm/s (5) 0.13 km/s5. What size downward electric field (in N/C) is required to balance the gravitational pull on an electron?(1) 5.9 × 10−5(2) 3.2 × 102(3) 9.3 × 10−20(4) 5.6 × 10−11(5) 5.7 × 10−126. Two charges are fixed in place on the x-axis, as shown. Charge Q1=+4 nC, and Q2= −1 nC. At what x-axis position (in m) should anelectron be placed so there is zero net force acting upon it? (Ignoregravity.) Select the closest answer.(1) 0.013 (2) 0.035 (3) 0.007 (4) −0.01 (5) 0.027. Which of the following statements is false:(1) For most conductors, the mobile charge carriers are electrons.(2) If the electric flux through a Gaussian surface is zero, then the electric field must be zero everywhere on thesurface.(3) The electrical potential midway between two oppositely charged point charges is exactly zero.(4) The electric field midway between two identical point charges is exactly zero.(5) Neutrons have mass but no charge.8. An aluminum wire and a silver wire have identical resistances and lengths. What is the ratio of the radius ofthe aluminum wire to that of the silver wire? The resistivities of aluminum and silver are 2.82 × 10−8Ω m and1.59 × 10−8Ω m, respectively.(1) 2.11 (2) 1.33 (3) 0.56 (4) 1.77 (5) 0.759. A spherical rubber (insulating) balloon has charge uniformly distributed on its surface. The balloon is then inflatedto three times its original size. Which of the following statements is correct? Assume the balloon begins and ends asa sphere.(1) At a point very near the outer surface of the balloon, the electric field increases(2) At a point far away from the balloon, the electric field decreases(3) At a point very near the outer surface of the balloon, the electric field remains constant(4) At a point far away from the balloon, the electric field increases(5) At a point far away from the balloon, the electric field doesn’t change31111 3111110. Three charges q1, q2and q3lie along a straight line as shown in thefigure. The charges q2and q1are opposite in sign and |q3| = 3|q2| =6|q1|. The distance between q2and q3is `. What is the distancebetween q1and q2when the electrostatic force on q1vanishes?(1) 1.37` (2) 0.54` (3) 0.98` (4) 0.76` (5) 1.11`11. A point charge Q1= +5 × 10−7C is initially located 0.1 cm from asecond (fixed) point charge Q2= −2.5 ×10−6C. If Q1follows the pathshown such that its final position is 1 cm from Q2, what is the changein its electric potential energy (in J)?(1) 13.5(2) −2.03 × 107(3) 2.03 × 107(4) −43.8(5) 10.112. Two hollow conducting shells surround a point charge Q = +5 nC, asshown. At a radius R = 0.6m from Q (i.e., outside the outer shell)the electric field is directed inward with magnitude 100 N/C. The totalcharge on the inner shell is −10 nC. What is the net charge (in nC) onthe outer shell? (Pick the closest answer.)(1) +1 (2) −4 (3) +9 (4) +4 (5) +613. The four capacitors in the diagram are arranged as shown and arecharged by a