Exam 28: Sources of Magnetic Field

As shown in the figure,a rectangular current loop is carrying current = 3.0 A,in the direction shown,and is located near a long wire carrying a current .The long wire is parallel to the sides of the rectangle.The rectangle loop has length 0.80 m and its sides are 0.10 m and 0.70 m from the wire,as shown.We measure that the net force on the rectangular loop is and is directed towards the wire. (a)What is the magnitude of the current I_w? (b)In which direction does I_w flow: from top to bottom or from bottom to top in the sketch?

A ring with a clockwise current (as seen from above the ring)is situated with its center directly above another ring,which has a counter-clockwise current,as shown in the figure.In what direction is the net magnetic force exerted on the top ring?

A vertical wire carries a current straight down.To the east of this wire,the magnetic field points

A long,straight wire with current flowing through it produces magnetic field strength at its surface.If the wire has a radius R,where within the wire is the field strength equal to of the field strength at the surface of the wire? Assume that the current density is uniform throughout the wire.

Two very long parallel wires in the xy-plane,a distance 2a apart,are parallel to the y-axis and carry equal currents I as shown in the figure.The +z direction points perpendicular to the xy-plane in a right-handed coordinate system.If both currents flow in the +y direction,which one of the graphs shown in the figure below best represents the z component of the net magnetic field,in the xy-plane,as a function of x? (Caution: These graphs are not magnetic field lines.)

Two circular coils of diameter 30.0 cm are parallel to each other and have their centers along the same line L but separated by 22.0 cm.When an experimenter views the coils along L,the coil closer to her carries a clockwise current of 2.50 A.Find the magnitude and sense (clockwise or counterclockwise)of the current needed in the other coil so that the net magnetic field on L midway between the two coils will have a magnitude of 4.10 µT and point away from the experimenter who is viewing the coils along L.

Two very long parallel wires in the xy-plane,a distance 2a apart,are parallel to the y-axis and carry equal currents I as shown in the figure.The +z direction points perpendicular to the xy-plane in a right-handed coordinate system.If the left current flows in the +y direction and the right current flows in the -y direction,which one of the graphs shown in the figure below best represents the z component of the net magnetic field,in the xy-plane,as a function of x? (Caution: These graphs are not magnetic field lines.)

The figure shows two long wires carrying equal currents I₁ and I₂ flowing in opposite directions.Which of the arrows labeled A through D correctly represents the direction of the magnetic field due to the wires at a point located at an equal distance d from each wire?

The figure shows the cross-section of a hollow cylinder of inner radius a = 5.0 cm and outer radius b = 7.0 cm.A uniform current density of 1.0 A/ cm² flows through the cylinder parallel to its axis.Calculate the magnitude of the magnetic field at a distance of d = 10 cm from the axis of the cylinder.

A type of transmission line for electromagnetic waves consists of two parallel conducting plates (assumed infinite in width)separated by a distance a.Each plate carries the same uniform surface current density of 16.0 A/m,but the currents run in opposite directions.What is the magnitude of the magnetic field between the plates at a point 1.00 mm from one of the plates if a = 0.800 cm? (μ₀ = 4π × 10^-7 T • m/A)

Two long parallel wires carry currents of 10 A in opposite directions.They are separated by 40 cm.What is the magnitude of the magnetic field in the plane of the wires at a point that is 20 cm from one wire and 60 cm from the other? (μ₀ = 4π × 10^-7 T • m/A)

The figure shows two long,parallel current-carrying wires.The wires carry equal currents A in the directions indicated and are located a distance d = 0.5 m apart.Calculate the magnitude and direction of the magnetic field at the point P that is located an equal distance d from each wire.