Exam 20: Magnetism

When the switch is closed in the circuit shown in the figure, the wire between the poles of the horseshoe magnet deflects upward. From this you can conclude that the left end of the magnet is

A flat circular coil of wire having 200 turns and diameter $6.0 \mathrm {~cm}$ carries a current of $7.0 \mathrm {~A}$ . It is placed in a magnetic field of $0.60 \mathrm {~T}$ with the plane of the coil making an angle of $30 ^ { \circ }$ with the magnetic field. What is the magnitude of the magnetic torque on the coil?

A flat circular wire loop of area $0.25 \mathrm {~m} ^ { 2 }$ carries a current of $5.0 \mathrm {~A}$ . This coil lies on a horizontal table with the current flowing in the counterclockwise direction when viewed from above. At this point, the earth's magnetic field is $1.2 \times 10 ^ { - 5 } \mathrm {~T}$ directed $60 ^ { \circ }$ below the horizontal. What is the magnitude of the torque that the earth's magnetic field exerts on this loop?

In a velocity selector consisting of perpendicular electric and magnetic fields, the speeds of the charged particles passing through the selector are increased or decreased until they are equal to the desired speed.

Two long parallel wires that are $0.40 \mathrm {~m}$ apart carry currents of $10 \mathrm {~A}$ in opposite directions. What is the magnetic field strength in the plane of the wires at a point that is $20 \mathrm {~cm}$ from one wire and 60 $\mathrm { cm }$ from the other? $\left( \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } \right)$

A rectangular coil, with corners labeled $\mathrm { ABCD }$ , has length $L$ and width $w$ . It is placed between the poles of a magnet, as shown in the figure If there is a current $I$ flowing through this coil in the direction shown, what is the direction of the force acting on section $A B$ of this coil?

A proton, moving east, enters a magnetic field. Because of this magnetic field the proton curves downward. We may conclude that the magnetic field must have a component

Consider an ideal solenoid of length L, N windings, and radius b (L is much longer than b). A current I is flowing through the wire windings. If the radius of the solenoid is doubled to 2b, but all The other quantities remain the same, the magnetic field inside the solenoid will

A long straight wire has a constant current flowing to the right. A rectangular metal loop is situated above the wire, and also has a constant current flowing through it, as shown in the figure. Which one of the following statements is true?

A proton, moving north, enters a magnetic field. Because of this field, the proton curves downward. We may conclude that the magnetic field must have a component

When you double the number of windings in an ideal solenoid while keeping all other parameters (radius, length and current) fixed, the magnetic field at the center of the solenoid will

A wire in the shape of an "M" lies in the plane of the paper. It carries a current of 2.0 A, flowing from A to E, as shown in the figure. It is placed in a uniform magnetic field of 0.65 T in the same Plane, directed as shown on the right side of the figure. The figure indicates the dimensions of the Wire. Note that AB is parallel to DE and to the baseline from which the magnetic field direction is Measured. What are the magnitude and direction of the force acting on section BC of this wire?

A wire is carrying current vertically downward. What is the direction of the force on this wire due to Earth's magnetic field?

At what distance from a long straight wire carrying a current of $5.0 \mathrm {~A}$ is the magnitude of the magnetic field due to the wire equal to the strength of Earth's magnetic field of about $5.0 \times 10 ^ { - 5 } \mathrm {~T}$ ? $\left( \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } \right)$

Two long parallel wires are $0.400 \mathrm {~m}$ apart and carry currents of $4.00 \mathrm {~A}$ and $6.00 \mathrm {~A}$ . What is the magnitude of the force per unit length that each wire exerts on the other wire? $\left( \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \right.$ . $\mathrm { m } / \mathrm { A }$ )

A proton is to orbit Earth at the equator using Earth's magnetic field to supply part of the necessary centripetal force. In what direction should the proton move?

Two long parallel wires carry currents of $20 \mathrm {~A}$ and $5.0 \mathrm {~A}$ in opposite directions. The wires are separated by $20 \mathrm {~cm}$ . At what point between the two wires do they produce the same strength magnetic field?

A long straight wire carrying a 4-A current is placed along the $x$ -axis as shown in the figure. What is the direction of the magnetic field at a point $P$ due to this wire?

A negatively-charged particle moves across a constant uniform magnetic field that is perpendicular to the velocity of the particle. The magnetic force on this particle

A wire in the shape of an "M" lies in the plane of the paper. It carries a current of 2.0 A, flowing from A to E, as shown in the figure. It is placed in a uniform magnetic field of 0.75 T in the same Plane, directed as shown on the right side of the figure. The figure indicates the dimensions of the Wire. Note that AB is parallel to DE and to the baseline from which the magnetic field direction is Measured. What are the magnitude and direction of the force acting on section AB of this wire?