Exam 30: Sources of the Magnetic Field

A current element (length = 1.0 cm)lies along the x axis with its center at x = 0 and carries a 20-A current in the positive x direction.Consider only the field of this current element and decide which combination of the following statements is correct.

A long solenoid (1500 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?

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 μT.What is the larger of the two currents?

When a ferromagnetic material that has been magnetized is brought to a temperature greater than the Curie temperature,what happens to its residual magnetism.

A long wire is known to have a radius greater than 4.0 mm and to carry a current uniformly distributed over its cross section.If the magnitude of the magnetic field is 0.285 mT at a point 4.0 mm from the axis of the wire and 0.200 mT at a point 10 mm from the axis,what is the radius of the wire?

Two wires,each having a weight per unit length of 1.0 × 10−⁴ N/m,are strung parallel,one 0.10 m above the other.If the wires carry the same current,though in opposite directions,how great must the current in each wire be for the magnetic field of the lower conductor to balance the weight of the upper conductor?

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?

A current-carrying 2.0-cm long segment of wire is inside a long solenoid (radius = 4.0 cm,n = 800 turns/m,current = 50 mA).The wire segment is oriented perpendicularly to the axis of the solenoid.If the current in the wire segment is 12 A,what is the magnitude of the magnetic force on this segment?

Two very long parallel wires carry currents in the positive x direction.One wire (current = 15 A)is coincident with the x axis.The other wire (current = 50 A)passes through the point (0,4.0 mm,0).What is the magnitude of the magnetic field at the point (0,0,3.0 mm)?

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.

If you were to travel parallel to an infinitely long straight wire with current I at the same velocity as the electrons in the wire at a distance a from the wire,the magnitude of the magnetic field (according to your measuring instruments)would be

Which of the following type(s)of materials is(are)repelled when a magnet is brought near by?

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 long straight wire (diameter = 2.0 mm)carries a current of 30 A.What is the magnitude of the magnetic field 2.5 mm from the axis of the wire?

Two long parallel wires are separated by 4.0 cm.One of the wires carries a current of 20 A and the other carries a 30-A current.Determine the magnitude of the magnetic force on a 2.0-m length of the wire carrying the greater current.

Two long parallel wires carry unequal currents in the same direction.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 μT.What is the larger of the two currents?

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

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

What is the magnitude of the magnetic field at point P if a = R and b = 2R?

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?