Chapter 20 Sample Multiple Choice Problems

Chapter 20 Sample Multiple Choice Problems Answers: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 1. d a c c d d d c b d c d a c a 1 T is equivalent to a. 1 Nm/A b. 1 NA/m c. 1 Vm/A d. 1 N/Am 2. A 2.0-m wire carrying a current of 0.60 A is oriented parallel to a uniform magnetic field of 0.50 T. What is the magnitude of the force it experiences? a. zero b. 0.60 N c. 0.15 N d. 0.30 N 3. A thin copper rod 1.0 m long has a mass of 0.050 kg and is in a magnetic field of 0.10 T. What minimum current in the rod is needed in order for the magnetic force to cancel the weight of the rod? a. 1.2 A b. 2.5 A c. 4.9 A d. 9.8 A 4. At a particular instant, an electron moves eastward at speed V in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is a. zero. b. directed upward. c. directed to the south. d. none of the above. 5. A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle will be maximum when the particle moves a. straight upward. b. straight downward. c. upward at an angle of 45ø above the horizontal. d. none of the above. 6. A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field vector. Ignoring the particle's weight, the particle will a. move in a straight line. b. follow a spiral path. c. move along a parabolic path. d. follow a circular path. 7. How much current must flow for 1.0X10-3 T of magnetic field to be present 1.0 cm from a wire? a. 0.050 A b. 9.2 A c. 16 A d. 50 A 8. A high power line carrying 1000 A generates what magnetic field at the ground, 10 m away? a. 4.7X10-6 T b. 6.4X10-6 T c. 2.0X10-5 T d. 5.6X10-5 T 9. Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on your right carries current toward you, and the wire on your left carries current away from you. From your point of view, the magnetic field at the point exactly midway between the two wires a. points up. b. points down. c. points toward you. d. is zero. 10. Two long parallel wires placed side-by-side on a horizontal table carry identical current straight toward you. From your point of view, the magnetic field at the point exactly between the two wires a. points up. b. points down. c. points toward you. d. is zero. 11. At double the distance from a long current-carrying wire, the strength of the magnetic field produced by that wire decreases to a. 1/8 of its original value. b. 1/4 of its original value. c. 1/2 of its original value. d. none of the above. 12. Two long parallel wires carry currents of 20 A and 5.0 A in opposite directions. The wires are separated by 0.20 m. What is the magnetic field midway between the two wires? a. 1.0X10-5 T b. 3.0X10-5 T c. 4.0X10-5 T d. 5.0X10-5 T 13. Two long parallel wires carry currents of 5.0 A and 8.0 A in the same direction. The wires are separated by 0.30 m. Find the magnetic force per unit length between the two wires. a. 2.7X10-5 N attractive b. 7.2X10-5 N attractive c. 2.7X10-5 N repulsive d. 7.2X10-5 N repulsive 14. Two long parallel wires carry currents of 5.0 A and 8.0 A in the opposite directions. The wires are separated by 0.30 m. Find the magnetic force per unit length between the two wires. a. 2.7X10-5 N attractive b. 7.2X10-5 N attractive c. 2.7X10-5 N repulsive d. 7.2X10-5 N repulsive 15. Two long parallel wires carry equal currents. The magnitude of the force between the wires is F. The current in each wire is now doubled. What is the magnitude of the new force bwteen the two wires? a. 4F b. 2F c. F/4 d. F/2