Question 1

The magnetic force on a current-carrying wire in a magnetic field is the strongest when

Accepted Answer

The magnetic force on a current-carrying wire is given by the Lorentz force law, which states that the force is maximum when the current direction is perpendicular to the magnetic field lines. This is because the force is proportional to the sine of the angle between the current direction and the magnetic field, reaching its maximum value when this angle is 90° (or perpendicular).

Question 2

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

Accepted Answer

The answer of When the switch is closed in the...

Question 3

After landing on an unexplored Klingon planet, Spock tests for the direction of the magnetic field by firing a beam of electrons in various directions and by recording the following observations:
Electrons moving upward feel a magnetic force in the northwest direction.
Electrons moving horizontally toward the north are pushed downward.
Electrons moving horizontally toward the southeast are pushed upward.
Mr) Spock therefore concludes that the magnetic field at this landing site is in which direction?

Accepted Answer

The direction of the magnetic force on moving charges (electrons in this case) can be determined using the right-hand rule. Given the observations:1. Electrons moving upward feeling a force toward the northwest implies the magnetic field is perpendicular to both the direction of motion (upward) and the force (northwest), suggesting a southwest to northeast direction.2. Electrons moving north being pushed downward further supports that the magnetic field is oriented from southwest to northeast, as a field in this direction would indeed push north-moving electrons downward.3. Electrons moving southeast and being pushed upward also align with a magnetic field directed from southwest to northeast, as this would cause a perpendicular upward force on southeast-moving electrons.Thus, the magnetic field direction that aligns with all observations is toward the southwest.

Question 4

For the horseshoe magnet shown in the figure, the left end is a north magnetic pole and the right end is a south magnetic pole. When the switch is closed in the circuit, which way will the wire between the poles of the horseshoe magnet initially deflect?

Accepted Answer

The answer of For the horseshoe magnet shown in the...

Question 5

A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle
Will be strongest when the particle moves

Accepted Answer

The magnetic force on a charged particle moving in a magnetic field is given by the Lorentz force law, which includes the cross product of the velocity of the particle and the magnetic field. The force is maximized when the angle between the velocity vector and the magnetic field vector is 90 degrees, which corresponds to motion in a plane parallel to Earth's surface when the magnetic field is straight upward.

Question 6

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

Accepted Answer

The magnetic force acts perpendicular to the velocity of the particle, changing its direction but not its speed, which is a form of acceleration.

Question 7

A rectangular coil, with corners labeled $A B C D$, 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 CD of this coil?

Accepted Answer

The answer of A rectangular coil, with corners labeled \(A...

Question 8

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field lines and takes time T for each circle. If the proton's speed tripled, what would now be its time to go around
Each circle?

Accepted Answer

The time period for a charge moving in a uniform magnetic field is independent of its speed. It only depends on the charge, mass of the particle, and the magnetic field strength.

Question 9

A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field lines. Ignoring the particle's weight, the particle will

Accepted Answer

When a charged particle moves perpendicular to a uniform magnetic field, it experiences a magnetic force perpendicular to its velocity, causing it to move in a circular path. This is due to the Lorentz force acting on the particle.

Question 10

If a calculated quantity has units of $\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }$, that quantity could be

Accepted Answer

The unit $\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }$ corresponds to the unit of a magnetic field, which is Tesla (T).

Question 11

A particle carrying a charge of +e travels in a circular path of radius R in a uniform magnetic field. If instead the particle carried a charge of +2e, the radius of the circular path would have been

Accepted Answer

The radius of the circular path of a charged particle in a magnetic field is inversely proportional to the charge of the particle. Doubling the charge from +e to +2e will halve the radius, making it $R / 2$.

Question 12

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

Accepted Answer

The magnetic force on a moving electron is given by the Lorentz force equation: F = q(v x B), where q is the charge of the electron, v is its velocity, and B is the magnetic field. The cross product of two vectors is a vector that is perpendicular to both of the original vectors. In this case, the velocity of the electron is to the south and the magnetic field is to the west, so the Lorentz force will be upward.

Question 13

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 BC of this coil?

Accepted Answer

The answer of A rectangular coil, with corners labeled \(\mathrm...

Question 14

At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Accepted Answer

The magnetic force on a charged particle moving in a magnetic field is given by the Lorentz force law, which is perpendicular to both the velocity of the particle and the magnetic field direction. Using the right-hand rule, with the proton moving east and the magnetic field directed downward, the force on the proton will be directed toward the north.

Question 15

The direction of the force on a current-carrying wire in a magnetic field is

Accepted Answer

The force on a current-carrying wire in a magnetic field is given by the right-hand rule, which states that the force is perpendicular to both the direction of the current and the magnetic field. This is described by Fleming's left-hand rule for motors or the right-hand rule for magnetic force, depending on the convention used.

Question 16

A proton has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

Accepted Answer

The answer of A proton has an initial velocity to...

Question 17

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

Accepted Answer

The answer of A wire is carrying current vertically downward....

Question 18

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle were traveling twice as fast, the radius of the circular path would be

Accepted Answer

The radius of the circular path $r$ for a charged particle moving in a magnetic field is given by $r = \frac{mv}{qB}$, where $m$ is the mass of the particle, $v$ is its velocity, $q$ is its charge, and $B$ is the magnetic field strength. Doubling the velocity ($v \rightarrow 2v$) would double the radius ($r \rightarrow 2r$), making the correct answer $2 R$.

Question 19

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?

Accepted Answer

The answer of A rectangular coil, with corners labeled \(\mathrm...

Question 20

At a particular instant, an electron moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Accepted Answer

The direction of the magnetic force on a moving charge in a magnetic field is given by the right-hand rule. Since the electron is moving east (right) and the magnetic field is downward, the force on a negative charge (electron) will be toward the south, opposite to the direction predicted by the right-hand rule for a positive charge.

Quiz 20: Magnetism

The magnetic force on a current-carrying wire in a magnetic field is the strongest when

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

For the horseshoe magnet shown in the figure, the left end is a north magnetic pole and the right end is a south magnetic pole. When the switch is closed in the circuit, which way will the wire between the poles of the horseshoe magnet initially deflect?

A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle Will be strongest when the particle moves

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 rectangular coil, with corners labeled $A B C D$ , 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 CD of this coil?

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field lines and takes time T for each circle. If the proton's speed tripled, what would now be its time to go around Each circle?

A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field lines. Ignoring the particle's weight, the particle will

If a calculated quantity has units of $\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }$ , that quantity could be

A particle carrying a charge of +e travels in a circular path of radius R in a uniform magnetic field. If instead the particle carried a charge of +2e, the radius of the circular path would have been

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

The direction of the force on a current-carrying wire in a magnetic field is

A proton has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

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

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle were traveling twice as fast, the radius of the circular path would be

At a particular instant, an electron moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Quiz 20: Magnetism

The magnetic force on a current-carrying wire in a magnetic field is the strongest when

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

For the horseshoe magnet shown in the figure, the left end is a north magnetic pole and the right end is a south magnetic pole. When the switch is closed in the circuit, which way will the wire between the poles of the horseshoe magnet initially deflect?

A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle Will be strongest when the particle moves

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 proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field lines and takes time T for each circle. If the proton's speed tripled, what would now be its time to go around Each circle?

A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field lines. Ignoring the particle's weight, the particle will

If a calculated quantity has units of NA⋅m\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }A⋅mN​ , that quantity could be

A particle carrying a charge of +e travels in a circular path of radius R in a uniform magnetic field. If instead the particle carried a charge of +2e, the radius of the circular path would have been

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

The direction of the force on a current-carrying wire in a magnetic field is

A proton has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component

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

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle were traveling twice as fast, the radius of the circular path would be

At a particular instant, an electron moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

If a calculated quantity has units of $\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }$ , that quantity could be