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Chapter 27: Sources of the Magnetic Field

Chapter 27: Sources of the Magnetic Field . Section 27-1: The Magnetic Field of Moving Point Charges.

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Chapter 27: Sources of the Magnetic Field

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  1. Chapter 27: Sources of the Magnetic Field Section 27-1: The Magnetic Field of Moving Point Charges

  2. A point charge is moving with constant speed 2 ×107 m/s along the x axis. It creates a magnetic field as it travels through a region where there is no external magnetic field. At t = 0, the charge is at x = 0 m and the magnitude of the magnetic field at x = 4 m is B0. The magnitude of the magnetic field at x = 4m when t = 0.1 s is • B0/2 • B0 • B0/4 • 2B0 • 4B0

  3. A point charge is moving with constant speed 2 ×107 m/s along the x axis. It creates a magnetic field as it travels through a region where there is no external magnetic field. At t = 0, the charge is at x = 0 m and the magnitude of the magnetic field at x = 4 m is B0. The magnitude of the magnetic field at x = 4m when t = 0.1 s is • B0/2 • B0 • B0/4 • 2B0 • 4B0

  4. The top diagram shows the velocity of a positively charged particle. Which arrow best represents the direction of the magnetic field due to the moving charge at r ?

  5. The top diagram shows the velocity of a positively charged particle. Which arrow best represents the direction of the magnetic field due to the moving charge at r ?

  6. The magnitude of the magnetic field due to the presence of a charged body • varies directly with the speed of the body. • varies directly with the charge carried by the body. • varies inversely with the square of the distance between the charged body and the field point. • depends on the magnetic properties of the space between the charged body and the field point. • is described by all of these.

  7. The magnitude of the magnetic field due to the presence of a charged body • varies directly with the speed of the body. • varies directly with the charge carried by the body. • varies inversely with the square of the distance between the charged body and the field point. • depends on the magnetic properties of the space between the charged body and the field point. • is described by all of these.

  8. A positively charged body is moving in the negative z direction as shown. What is the direction of the magnetic field due to the motion of this charged body at point P?

  9. A positively charged body is moving in the negative z direction as shown. What is the direction of the magnetic field due to the motion of this charged body at point P?

  10. A positively charged body is moving in the positive x direction as shown. The direction of the magnetic field at the origin due to the motion of this charged body is • 1 • 2 • 3 • 4 • None of these is correct, as this charged body does not create a magnetic field along the axis of its motion.

  11. A positively charged body is moving in the positive x direction as shown. The direction of the magnetic field at the origin due to the motion of this charged body is • 1 • 2 • 3 • 4 • None of these is correct, as this charged body does not create a magnetic field along the axis of its motion.

  12. At the instant the positively charged body is at the origin, the magnetic field at point P due to the motion of this charged body is in the negative x direction. The charged body must be moving • in the negative z direction. • in the positive y direction. • in the positive x direction. • in the negative y direction. • in the positive z direction.

  13. At the instant the positively charged body is at the origin, the magnetic field at point P due to the motion of this charged body is in the negative x direction. The charged body must be moving • in the negative z direction. • in the positive y direction. • in the positive x direction. • in the negative y direction. • in the positive z direction.

  14. At the instant the negatively charged body is at the origin, the magnetic field at point P due to its motion is in the negative x direction. The charged body must be moving • in the negative z direction. • in the positive y direction. • in the positive x direction. • in the negative y direction. • in the positive z direction.

  15. At the instant the negatively charged body is at the origin, the magnetic field at point P due to its motion is in the negative x direction. The charged body must be moving • in the negative z direction. • in the positive y direction. • in the positive x direction. • in the negative y direction. • in the positive z direction.

  16. Two positively charged bodies are moving in opposite directions on parallel paths that lie in the xz plane. Their speeds are equal and their trajectories are equidistant from the x axis. The magnetic field at the origin, due to the motion of these charged bodies will be • in the +x direction. • in the +y direction. • in the−y direction. • in the +z direction. • zero.

  17. Two positively charged bodies are moving in opposite directions on parallel paths that lie in the xz plane. Their speeds are equal and their trajectories are equidistant from the x axis. The magnetic field at the origin, due to the motion of these charged bodies will be • in the +x direction. • in the +y direction. • in the−y direction. • in the +z direction. • zero.

  18. Chapter 27: Sources of the Magnetic Field Section 27-2: The Magnetic Field of Currents: The Biot-Savart Law

  19. Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is • zero. • into the page. • out of the page. • toward the top or bottom of the page. • toward one of the two wires.

  20. Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is • zero. • into the page. • out of the page. • toward the top or bottom of the page. • toward one of the two wires.

  21. What is the direction of the magnetic field around a wire carrying a current perpendicularly into this page? • The field is parallel to and in the same direction as the current flow. • It is parallel to but directed opposite to the current flow. • It is counterclockwise around the wire in the plane of the page. • It is clockwise around the wire in the plane of the page. • None of these is correct.

  22. What is the direction of the magnetic field around a wire carrying a current perpendicularly into this page? • The field is parallel to and in the same direction as the current flow. • It is parallel to but directed opposite to the current flow. • It is counterclockwise around the wire in the plane of the page. • It is clockwise around the wire in the plane of the page. • None of these is correct.

  23. A wire carries an electric current straight upward. What is the direction of the magnetic field due to the current north of the wire? • north • east • west • south • upward

  24. A wire carries an electric current straight upward. What is the direction of the magnetic field due to the current north of the wire? • north • east • west • south • upward

  25. The Biot–Savart law is similar to Coulomb's law in that both • are inverse square laws. • include the permeability of free space. • deal with excess charges. • are not electrical in nature. • are described by all of these.

  26. The Biot–Savart law is similar to Coulomb's law in that both • are inverse square laws. • include the permeability of free space. • deal with excess charges. • are not electrical in nature. • are described by all of these.

  27. Two current-carrying wires are perpendicular to each other. The current in one flows vertically upward and the current in the other flows horizontally toward the east. The horizontal wire is 1 m south of the vertical wire. What is the direction of the net magnetic force on the horizontal wire? • north • east • west • south • There is no net magnetic force on the horizontal wire.

  28. Two current-carrying wires are perpendicular to each other. The current in one flows vertically upward and the current in the other flows horizontally toward the east. The horizontal wire is 1 m south of the vertical wire. What is the direction of the net magnetic force on the horizontal wire? • north • east • west • south • There is no net magnetic force on the horizontal wire.

  29. Each of the figures shown is the source of a magnetic field. In which figure does the magnetic dipole vector point in the direction of the negative x axis? (Note: in C and D the arrows show the direction of the current.)

  30. Each of the figures shown is the source of a magnetic field. In which figure does the magnetic dipole vector point in the direction of the negative x axis? (Note: in C and D the arrows show the direction of the current.)

  31. The sketch shows a circular coil in the xz plane carrying a current I. The direction of the magnetic field at point O is • +x • –x • +y • –y • –z

  32. The sketch shows a circular coil in the xz plane carrying a current I. The direction of the magnetic field at point O is • +x • –x • +y • –y • –z

  33. In a circular loop of wire lying on a horizontal floor, the current is constant and, to a person looking downward, has a clockwise direction. The accompanying magnetic field at the center of the circle is directed • horizontally and to the east. • horizontally and to the north. • vertically upward. • parallel to the floor. • vertically downward.

  34. In a circular loop of wire lying on a horizontal floor, the current is constant and, to a person looking downward, has a clockwise direction. The accompanying magnetic field at the center of the circle is directed • horizontally and to the east. • horizontally and to the north. • vertically upward. • parallel to the floor. • vertically downward.

  35. An electron beam travels counterclockwise in a circle of radius R in the magnetic field produced by the Helmholtz coils as shown. If you increase the current in the Helmholtz coils, the electron beam will • increase its radius. • decrease its radius. • maintain the same radius.

  36. An electron beam travels counterclockwise in a circle of radius R in the magnetic field produced by the Helmholtz coils as shown. If you increase the current in the Helmholtz coils, the electron beam will • increase its radius. • decrease its radius. • maintain the same radius.

  37. Which graph best represents the strength of the magnetic field B between the coils of radius R of a Helmholtz pair as a function of distance along the axis of the pair?

  38. Which graph best represents the strength of the magnetic field B between the coils of radius R of a Helmholtz pair as a function of distance along the axis of the pair?

  39. An electron beam travels counterclockwise in a circle in the magnetic field produced by the Helmholtz coils, as shown. Assuming that the earth's field is downward, one can conclude that • the Helmholtz field equals the earth's field. • the current in the coils moves in the same direction as the electron beam. • the current in the coils moves in the direction opposite to the electron beam. • the Helmholtz field curves in the direction of the electron beam. • the Helmholtz field curves in a direction opposite to the electron beam.

  40. An electron beam travels counterclockwise in a circle in the magnetic field produced by the Helmholtz coils, as shown. Assuming that the earth's field is downward, one can conclude that • the Helmholtz field equals the earth's field. • the current in the coils moves in the same direction as the electron beam. • the current in the coils moves in the direction opposite to the electron beam. • the Helmholtz field curves in the direction of the electron beam. • the Helmholtz field curves in a direction opposite to the electron beam.

  41. When the positive current in a long wire is flowing in a direction from S to N, it creates a magnetic field below the wire that is directed • from E to W. • from N to S. • from NE to SW. • from S to N. • from W to E.

  42. When the positive current in a long wire is flowing in a direction from S to N, it creates a magnetic field below the wire that is directed • from E to W. • from N to S. • from NE to SW. • from S to N. • from W to E.

  43. The current in a wire along the x axis flows in the positive x direction. If a proton, located as shown in the figure, has an initial velocity in the positive z direction, it experiences • a force in the direction of positive x. • a force in the direction of negative x. • a force in the direction of positive z. • a force in the direction of positive y. • no force.

  44. The current in a wire along the x axis flows in the positive x direction. If a proton, located as shown in the figure, has an initial velocity in the positive z direction, it experiences • a force in the direction of positive x. • a force in the direction of negative x. • a force in the direction of positive z. • a force in the direction of positive y. • no force.

  45. A long conductor carrying current I lies in the xz plane parallel to the z axis. The current travels in the negative z direction, as shown in the figure. The vector that represents the magnetic field at the origin O is

  46. A long conductor carrying current I lies in the xz plane parallel to the z axis. The current travels in the negative z direction, as shown in the figure. The vector that represents the magnetic field at the origin O is

  47. Two straight wires perpendicular to the plane of this page are shown in the figure. The currents in the wires are the same. The current in M is into the page and the current in N is out of the page. The vector that represents the resultant magnetic field at point P is

  48. Two straight wires perpendicular to the plane of this page are shown in the figure. The currents in the wires are the same. The current in M is into the page and the current in N is out of the page. The vector that represents the resultant magnetic field at point P is

  49. Current-carrying wires are located along two edges of a cube with the directions of the currents as indicated. Which vector indicates the resultant magnetic field at the corner of the cube?

  50. Current-carrying wires are located along two edges of a cube with the directions of the currents as indicated. Which vector indicates the resultant magnetic field at the corner of the cube?

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