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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
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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
