Exam 22: Magnetic Forces and Magnetic Fields

A charged particle (mass = M,charge = Q > 0)moves in a region of space where the magnetic field has a constant magnitude of B and a downward direction.What is the magnetic force on the particle at an instant when it is moving horizontally toward the north with speed V?

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

We find that N current loops are coplanar and coaxial.The first has radius a and current I.The second has radius 2a and current 2I,and the pattern is repeated up to the Nth,which has radius Na and current NI.The current in each loop is counterclockwise as seen from above.The magnitude of the magnetic field at the center of the loops is

A straight wire of length L carries a current I in the positive z direction in a region where the magnetic field is uniform and specified by B_x = 3B,B_y = -2B,and B_z = B,where B is a constant.What is the magnitude of the magnetic force on the wire?

When the number of turns in a solenoid and its length are both doubled,the ratio of the magnitude of the new magnetic field inside to the magnitude of the original magnetic field inside is:

By using a compass to measure the magnetic field direction at various points adjacent to a long straight wire,you can show that the wire's magnetic field lines are

A square loop (L = 0.20 m)consists of 50 closely wrapped turns,each carrying a current of 0.50 A.The loop is oriented as shown in a uniform magnetic field of 0.40 T directed in the positive y direction.What is the magnitude of the torque on the loop?

Equal currents of magnitude I travel out of the page in wire M and into the page in wire N.Eight directions are indicated by letters A through H. The direction of the magnetic field at point P is

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 into the page,the direction of the magnetic field at P is closest to the direction of

A long solenoid (n = 1 200 turns/m,radius = 2.0 cm)has a current of a 0.30 A in its winding.A long wire carrying a current of 20 A is parallel to and 1.0 cm from the axis of the solenoid.What is the magnitude of the resulting magnetic field at a point on the axis of the solenoid?

A 2.0-cm length of wire centered on the origin carries a 20-A current directed in the positive y direction.Determine the magnetic field at the point x = 5.0 m on the x-axis.

Equal currents of magnitude I travel out of the page in wires M and N.Eight directions are indicated by letters A through H. The direction of the magnetic field at point P is

The figure shows a cross section of three parallel wires each carrying a current of 15 A.The currents in wires A and C are out of the paper,while that in wire B is into the paper.If the distance R = 5.0 mm,what is the magnitude of the force on a 4.0-m length of wire C?

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 2.0-m wire carries a current of 15 A directed along the positive x axis in a region where the magnetic field is uniform and given by B = (30 $\hat { \mathbf { i } }$ -0 40 $\tilde{\mathbf{j}}$ )mT.What is the resulting magnetic force on the wire?

A toroid is made of 2 000 turns of wire of radius 2.00 cm formed into a donut shape of inner radius 10.0 cm and outer radius 14.0 cm.When a 30.0-A current is present in the toroid,the magnetic field at a distance of 11.0 cm from the center of the toroid is

A long straight wire carries a current of 40 A in a region where a uniform external magnetic field has a 30- $\mu$ T magnitude and is parallel to the current.What is the magnitude of the resultant magnetic field at a point that is 20 cm from the wire?

A straight 10-cm wire bent at its midpoint so as to form an angle of 90 $\degree$ carries a current of 10 A.It lies in the xy plane in a region where the magnetic field is in the positive z direction and has a constant magnitude of 3.0 mT.What is the magnitude of the magnetic force on this wire?

Each of two parallel wires separated by 8.0 mm carries a 20-A current.These two currents are oppositely directed.Determine the magnitude of the magnetic field at a point that is 5.0 mm from each of the wires.

A long wire carries a current of 3.0 A along the axis of a long solenoid (radius = 3.0 cm,n = 900 turns/m,current = 30 mA).What is the magnitude of the magnetic field at a point 2.0 cm from the axis of the solenoid? Neglect any end effects.