Exam 22: Magnetic Forces and Magnetic Fields

Three coplanar parallel straight wires carry equal currents I as shown below.The current in the outer wires is directed to the right,and that in the middle wire is directed to the left.Each pair of wires is a distance a apart.The direction of the magnetic force on the middle wire

The magnetic field in a region of space is parallel to the surface of a long flat table.Imagine that this page is lying flat on the table.When current is present in the coil,which is lying on the table,the coil tends to rotate so that the left side moves up and the right side moves down.The magnetic field is

On the average,in a ferromagnetic domain permanent atomic magnetic moments are aligned ____ to one another.

The point P lies along the perpendicular bisector of the line connecting two long straight wires S and T perpendicular to the page.A set of directions A through H is shown next to the diagram.When the two equal currents in the wires are directed up out of the page,the direction of the magnetic field at P is closest to the direction of

The diagram below shows the position of a long straight wire perpendicular to the page and a set of directions labeled A through H. When the current in the wire is directed up out of the page,the direction of the magnetic field at point P is

A solenoid consists of 100 circular turns of copper wire.Parts of three turns,A,B and C,are shown below. When a current flows through the coil,

A segment of wire carries a current of 25 A along the x axis from x = -2.0 m to x = 0 and then along the y axis from y = 0 to y = 3.0 m.In this region of space,the magnetic field is equal to 40 mT in the positive z direction.What is the magnitude of the force on this segment of wire?

The boundary shown is that of a uniform magnetic field directed in the positive z direction.An electron enters the magnetic field with a velocity pointing along the x axis and exits 0.63 $\mu$ s later at point A.What is the magnitude of the magnetic field?

Three long,straight,parallel wires each carry a current of 10 A in the positive x direction.If the distance between each wire and the other two is 10 cm,what is the magnitude of the magnetic force on a 20-cm length of either of the wires?

A long solenoid (n = 80 turns/cm)carries a current of 70 mA.Determine the magnitude of the magnetic field inside the solenoid.

Equal charges,one at rest,the other having a velocity of 10⁴ m/s,are released in a uniform magnetic field.Which charge has the largest force exerted on it by the magnetic field?

A straight wire (length = 8.0 m)is bent to form a square.If the wire carries a current of 20 A,what is the magnitude of the magnetic field at the center of the square?

A conducting rod with a square cross section (3.0 cm *3.0 cm)carries a current of 60 A that is uniformly distributed across the cross section.What is the magnitude of the (line)integral $\oint \mathrm { B } \cdot d \mathbf { s }$ around a square path (1.5 cm *1.5 cm)if the path is centered on the center of the rod and lies in a plane perpendicular to the axis of the rod?

What is the radius of curvature of the path of a 3.0-keV proton in a perpendicular magnetic field of magnitude 0.80 T?

Which diagram correctly shows the magnetic field lines created by a circular current loop in which current flows in the direction shown?

A 0.50-m long solenoid consists of 1 000 turns of copper wire wound with a 4.0 cm radius.When the current in the solenoid is 18 A,the magnetic field at a point 1.0 cm from the central axis of the solenoid is

A rectangular coil (0.20 m * 0.80 m)has 200 turns and is in a uniform magnetic field of 0.30 T.When the orientation of the coil is varied through all possible positions,the maximum torque on the coil by magnetic forces is 0.080 N . m.What is the current in the coil?

Two long parallel wires each carry a current of 5.0 A directed to the east.The two wires are separated by 8.0 cm.What is the magnitude of the magnetic field at a point that is 5.0 cm from each of the wires?

Two long straight wires carry currents perpendicular to the xy plane.One carries a current of 50 A and passes through the point x = 5.0 cm on the x axis.The second wire has a current of 80 A and passes through the point y = 4.0 cm on the y axis.What is the magnitude of the resulting magnetic field at the origin?

A long hollow cylindrical conductor (inner radius = 2.0 mm,outer radius = 4.0 mm)carries a current of 12 A distributed uniformly across its cross section.A long wire which is coaxial with the cylinder carries an equal current in the same direction.What is the magnitude of the magnetic field 3.0 mm from the axis?