Cover Page PHYSICS 132 Sample Final 200 points 5 Problems on 4 Pages and 20 Multiple Choice/Short Answer Questions on 5 pages 1 hour, 48 minutes Student Name: ________________________________ Recitation Instructor (circle one): name1 name2 name3 name4 • Write your name and circle the name of your recitation instructor on every page. The pages of this exam will be separated and each page graded by a different instructor. You must have your name on each sheet to receive a grade. • Show your work. Although an answer may seem obvious, you must still justify your results. Problem 1 _______ Problem 2 _______ Problem 3 _______ Problem 4 _______ M.C. _______ Total _______Physics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 1 Problem 1, 25 points total. A long conducting cylindrical shell is concentric about a long wire. The shell has outer radius c and inner radius b, while the wire has radius a: a < b < c. The wire has a uniform current 5i into the page and the shell has a uniform current 8i out of the page. A cross-section of the arrangement is shown to the right. Use Ampere’s Law to answer the following questions. (a) What is the magnetic field, B(r), for r < a? (b) What is the magnetic field, B(r), for a < r < b? (c) What is the magnetic field, B(r), for r > c? (d) At what value of r does the magnetic field have the largest magnitude? bc aPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 2 Problem 2, 13 points total. Consider the arrangement of wires shown in the figure. There are four straight sections and two sections that are quarter-circles that lie on a common circle of radius R. Point P is at the center of the circle. R = 2.0 m, i = 8.0 A. What is the magnetic field at location P? Problem 3, 13 points total. A long wire carrying a current 2i runs through the center of a long solenoid carrying a current 3i, as shown in cross-section. The solenoid has n turns per unit length. What is the magnetic field a distance d above the wire? P R2i3i d 3i2iPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 3 Problem 4, 24 points total. Three very long wires of length L lie parallel to each other, and are arranged through three of the vertices of a square with sides of length a. A cross-section of this arrangement is shown in the figure. The currents and their directions are marked. Neglect the effect of fringing fields. (a) What is the magnetic force, F, on the leftmost wire due to the other two wires? (b) Suppose we move the leftmost wire to the center of the square. Now what is the magnetic force on it? 3i3iiaaaa 3i3iiaaa aPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 4 Problem 5, 25 points total. A conducting square loop with sides of length L is pulled up by a string at constant speed v in a uniform magnetic field, B, going into the page as shown. The loop’s resistance is R and its mass is m. (a) What is the current in the loop before it reaches the dotted line? Also indicate its direction. (b) What is the current in the loop after the top of the loop passes above the line, but before the bottom does? Also indicate its direction. (c) The string is cut and the loop falls down. It reaches terminal velocity before the top of the loop passes back into the magnetic field. What is the magnitude of its terminal velocity? vBLPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 5 MULTIPLE CHOICE/SHORT ANSWER SECTION (100 points) There is no partial credit and you do not need to show any work. 1. Electrons are going around a circle in a counterclockwise direction as shown. They produce a magnetic field whose direction at the center of the circle is: A) into the page. B) out of the page. C) to the left. D) to the right. E) undefined, because the magnitude of the field is zero. 2. Four 20 Ω resistors are connected in parallel and the combination is connected to a 20 V emf device. The current in the device is: A) 0.25 A B) 1.0 A C) 4.0 A D) 5.0 A E) 100 A 3. Pulling the plates of an isolated charged capacitor apart: A) increases the capacitance. B) does not affect the capacitance. C) increases the potential difference. D) does not affect the potential difference. E) decreases the potential difference. 4. An electron is moving north in a region where the magnetic field is south. The magnetic force exerted on the electron is: A) zero B) up C) down D) east E) west electronPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: name1 name2 name3 name4 Page 6 5. The diagram shows the electric field lines in a region of space containing two small charged spheres (Y and Z). X marks a location in space. A) Y is negative and Z is positive. B) the magnitude of the electric field is the same everywhere. C) the electric field is strongest midway between Y and Z. D) a small negatively charged body placed at X would be pushed to the right. E) Y and Z must have the same sign. 6. 10 C of charge are placed on a spherical conducting shell. A -3 C point charge is placed at the center of the cavity. What is the net charge on the inner surface of the shell is? 7. An electron traveling north enters a region where the electric field is uniform and points north. The electron: A) speeds up D) veers west B) slows down E) continues with the same speed in the same direction C) veers east 8. A long straight wire is in the plane of a rectangular conducting loop. The straight wire carries an increasing current in the direction shown. The current in the rectangle is: A) zero B) clockwise C) counterclockwise D) clockwise in the left side and counterclockwise in the right side E) counterclockwise in the left side and clockwise in the right side Y ZXPhysics 132, Sample Final Page Score _______ Name: _____________________ Recitation Instructor: