Exam 22: Magnetic Forces and Magnetic Fields

A straight wire is bent into the shape shown.Determine the net magnetic force on the wire when the current I travels in the direction shown in the magnetic field $\vec { B }$ .

A hollow cylindrical (inner radius = 2.0 mm,outer radius = 4.0 mm)conductor carries a current of 24 A parallel to its axis.This current is uniformly distributed over a cross section of the conductor.Determine the magnitude of the magnetic field at a point that is 5.0 mm from the axis of the conductor.

A long straight wire (diameter = 2.0 mm)carries a current of 25 A.What is the magnitude of the magnetic field 0.50 mm from the axis of the wire?

The following statements all refer to the human brain when mental activity is occurring.Which statement is correct?

A current of 4.0 A is maintained in a single circular loop having a circumference of 80 cm.An external magnetic field of 2.0 T is directed so that the angle between the field and the plane of the loop is 20 $\degree$ .Determine the magnitude of the torque exerted on the loop by the magnetic forces acting upon it.

The field at (0,0,1.0 m)is in the negative y direction.

A magnetic field is directed out of the page.Two charged particles enter from the top and take the paths shown in the figure.Which statement is correct?

Two long parallel wires carry unequal currents in opposite directions.The ratio of the currents is 3 to 1.The magnitude of the magnetic field at a point in the plane of the wires and 10 cm from each wire is 4.0 $\mu$ T.What is the larger of the two currents?

What is the magnitude of the magnetic field at point P in the figure if a = 2.0 cm,b = 4.5 cm,and I = 5.0 A?

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 particle (mass = 6.0 mg)moves with a speed of 4.0 km/s in a direction that makes an angle of 37 $\degree$ above the positive x axis in the xy plane.At the instant it enters a magnetic field of (5.0 $\hat { \mathbf { i } }$ )mT it experiences an acceleration of (8.0 $\hat { k }$ )m/s².What is the charge of the particle?

An electron moves in a region where the magnetic field is uniform,has a magnitude of 60 $\mu$ T,and points in the positive x direction.At t = 0 the electron has a velocity that has an x component of 30 km/s,a y component of 40 km/s,and a z component of zero.What is the radius of the resulting helical path?

A long solenoid (1 500 turns/m)carries a current of 20 mA and has an inside diameter of 4.0 cm.A long wire carries a current of 2.0 A along the axis of the solenoid.What is the magnitude of the magnetic field at a point that is inside the solenoid and 1.0 cm from the wire?

A magnetic field of 2.00 T is applied to a bubble chamber to make the tracks of protons and other charged particles identifiable by the radius of the circles they move in.If a high-energy proton moves along an arc of a 3.30-m circle,what is the momentum of the proton? [q = 1.60 *10 ^{- 19} C,m = 1.67 *10 ^{- 27} kg]

Two long parallel wires lie in the xz plane. One wire passes through the point (+2 m, 0, 0) and the other through the point (+2 m, 0, 0). The wires carry equal currents in the positive z direction. 1. The magnetic field at (3 m, 0, 0) is in the negative y direction. 2. The magnetic field at (1 m, 0, 0) is in the positive y direction. 3. The magnetic field at (+1 m, 0, 0) is in the positive y direction. 4. The magnetic field at (+3 m, 0, 0) is in the negative y direction.

The segment of wire (total length = 6R,including the incoming and outgoing portions of the wire)is formed into the shape shown and carries a current I.What is the magnitude of the resulting magnetic field at the point P?

Each of two long straight parallel wires separated by a distance of 16 cm carries a current of 20 A in the same direction.What is the magnitude of the resulting magnetic field at a point that is 10 cm from each wire?

At what speed would a proton need to circle the Earth at a height of 1 000 km above the equator if the Earth's magnetic field is horizontal and directed north-south,with an intensity of 4.00 *10 ^{- 8} T? (The radius of the Earth is 6 400 km and the charge and mass of the proton are q = 1.60 *10 ^{- 19} C and m_p = 1.67 * 10 ^{- 27} kg.Ignore relativistic corrections. )

Two long parallel wires are separated by 6.0 mm.The current in one of the wires is twice the other current.If the magnitude of the force on a 3.0-m length of one of the wires is equal to 8.0 $\mu$ N,what is the greater of the two currents?

A proton is accelerated from rest through a potential difference of 150 V.It then enters a region of uniform magnetic field and moves in a circular path (radius = 12 cm).What is the magnitude of the magnetic field in this region?