Exam 29: The Magnetic Field

Two long parallel wires carry currents of 20 A and 5.0 A in opposite directions.The wires are separated by 0.20 m.What is the magnitude of the magnetic field midway between the two wires? (μ₀ = 4π × 10^-7 T ∙ m/A)

Three particles travel through a region of space where the magnetic field is out of the page,as shown in the figure.The electric charge of each of the three particles is,respectively,

A point charge Q moves on the x-axis in the positive direction with a speed of A point P is on the y-axis at The magnetic field produced at the point P,as the charge moves through the origin,is equal to What is the charge Q? (μ₀ = 4π × 10^-7 T ∙ m/A)

A thin copper rod that is 1.0 m long and has a mass of 0.050 kg is in a magnetic field of 0.10 T.What minimum current in the rod is needed in order for the magnetic force to cancel the weight of the rod?

The magnetic field at a distance of 2 cm from a current carrying wire is 4 μT.What is the magnetic field at a distance of 4 cm from the wire?

A wire carrying a current is shaped in the form of a circular loop of radius If the magnetic field strength that this current produces at the center of the loop is what is the magnitude of the current that flows through the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

A wire carries a 4.0-A current along the +x-axis through a magnetic field = (5.0 + 7.0 )T.If the wire experiences a force of 30 N as a result,how long is the wire?

A rigid rectangular loop,which measures 0.30 m by 0.40 m,carries a current of 5.5 A,as shown in the figure.A uniform external magnetic field of magnitude 2.9 T in the negative x direction is present.Segment CD is in the xz-plane and forms a 35° angle with the z-axis,as shown.Find the magnitude of the external torque needed to keep the loop in static equilibrium.

A proton,with mass 1.67 × 10^-27 kg and charge +1.6 × 10^-19 C,is sent with velocity 7.1 × 10⁴ m/s in the +x direction into a region where there is a uniform electric field of magnitude 730 V/m in the +y direction.What are the magnitude and direction of the uniform magnetic field in the region,if the proton is to pass through undeflected? Assume that the magnetic field has no x-component and neglect gravitational effects.

A rigid circular loop has a radius of 0.20 m and is in the xy-plane.A clockwise current I is carried by the loop,as shown.The magnitude of the magnetic moment of the loop is 0.75 A · m².A uniform external magnetic field,B = 0.20 T in the positive x-direction,is present. (a)What is the current in the loop? (b)Find the magnitude of the magnetic torque exerted on the loop. (c)If the loop is released from rest,in what direction will points a and c initially move?

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

A beam of electrons is accelerated through a potential difference of 10 kV before entering a region having uniform electric and magnetic fields that are perpendicular to each other and perpendicular to the direction in which the electron is moving.If the magnetic field in this region has a value of 0.010 T,what magnitude of the electric field is required if the particles are to be undeflected as they pass through the region?

A long straight very thin wire on the y-axis carries a 10-A current in the positive y-direction.A circular loop 0.50 m in radius,also of very thin wire and lying in the yz-plane,carries a 9.0-A current,as shown.Point P is on the positive x-axis,at a distance of 0.50 m from the center of the loop.What is the magnetic field vector at point P due to these two currents? (μ₀ = 4π × 10^-7 T ∙ m/A)

A solenoid of length 18 cm consists of closely spaced coils of wire wrapped tightly around a wooden core.The magnetic field strength is inside the solenoid near its center when a certain current flows through the coils.If the coils of the solenoid are now pulled apart slightly,stretching it to without appreciably changing the size of the coils,what does the magnetic field become near the center of the solenoid when the same current flows through the coils? (μ₀ = 4π × 10^-7 T ∙ m/A)

A solenoid is wound with 970 turns on a form 4.0 cm in diameter and 50 cm long.The windings carry a current I in the sense that is shown in the figure.The current produces a magnetic field,of magnitude near the center of the solenoid.Find the current in the solenoid windings.

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.(μ₀ = 4π × 10^-7 T ∙ m/A)

A very long,hollow,thin-walled conducting cylindrical shell (like a pipe)of radius R carries a current along its length uniformly distributed throughout the thin shell.Which one of the graphs shown in the figure most accurately describes the magnitude B of the magnetic field produced by this current as a function of the distance r from the central axis?

A very long thin wire produces a magnetic field of at a distance of from the central axis of the wire.What is the magnitude of the current in the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

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.(μ₀ = 4π × 10^-7 T ∙ m/A)

An L-shaped metal machine part is made of two equal-length segments that are perpendicular to each other and carry a 4.50-A current as shown in the figure.This part has a total mass of 3.80 kg and a total length of 3.00 m,and it is in an external 1.20-T magnetic field that is oriented perpendicular to the plane of the part,as shown.What is the magnitude of the NET magnetic force that the field exerts on the part?