Question 1

An ion with a charge of +3.2 *10^?19 C is in region where a uniform electric field of 5 F*10^4.V/m is perpendicular to a uniform magnetic field of 0.8 T.If its acceleration is zero then its speed must be:

Accepted Answer

The force on the ion due to the electric field is given by:
F = qE = (3.2 × 10^-19 C)(5 V/m) = 1.6 × 10^-18 N

The force on the ion due to the magnetic field is given by:
F = qvB = (3.2 × 10^-19 C)v(0.8 T) = 2.56 × 10^-19 v N

Since the acceleration of the ion is zero, the two forces must be equal in magnitude and opposite in direction:

1.6 × 10^-18 N = 2.56 × 10^-19 v N

Solving for v gives:

v = 6.25 × 10^6 m/s

The answer is D, 6.3 × 10^5 m/s.

Question 2

A magnetic field exerts a force on a charged particle:

Accepted Answer

A magnetic field exerts a force on a charged particle if the particle is moving across the field lines. The force is perpendicular to both the direction of the magnetic field and the velocity of the particle. If the particle moves parallel to the field lines or is at rest, no magnetic force is exerted.

Question 3

An electron enters a region of uniform perpendicular  and  fields.It is observed that the velocity  of the electron is unaffected.A possible explanation is:

Accepted Answer

D

Question 4

Units of a magnetic field might be:

Accepted Answer

The answer of Units of a magnetic field might be:
...

Question 5

An electron is travelling in the positive x direction.A uniform electric field  is in the negative y direction.If a uniform magnetic field with the appropriate magnitude and direction also exists in the region, the total force on the electron will be zero.The appropriate direction for the magnetic field is:

Accepted Answer

The force on a charged particle moving in a magnetic field is given by the formula:

F = qvB sin(theta)

where 'q' is the charge of the particle, 'v' is the velocity of the particle, 'B' is the magnetic field, and theta is the angle between the velocity and the magnetic field.

In this case, the electron is travelling in the positive x direction and the electric field is in the negative y direction. Since the electric field is perpendicular to the magnetic field, the magnetic force will be perpendicular to both the velocity and the electric field.

To cancel out the electric force, the magnetic force must be equal in magnitude but opposite in direction. Since the magnetic force is perpendicular to the velocity, the angle theta must be 90 degrees. To achieve this, the magnetic field must be into the page, which is perpendicular to both the x direction of motion and the y direction of the electric field. Thus, the correct answer is C: into the page.

Question 6

An electron and a proton are both initially moving with the same speed and in the same direction at 90˚ to the same uniform magnetic field.They experience magnetic forces, which are initially:

Accepted Answer

The magnetic force on a charged particle is given by $F = qvB\sin(\theta)$, where $q$ is the charge, $v$ is the velocity, $B$ is the magnetic field strength, and $\theta$ is the angle between the velocity and the magnetic field. Since the electron and proton have equal and opposite charges and are moving at the same speed in the same direction relative to the magnetic field, the magnitudes of their forces will be equal, but the directions will be opposite due to their opposite charges.

Question 7

J.J.Thomson's experiment, involving the motion of an electron beam in mutually perpendicular  and  fields, gave the value of:

Accepted Answer

J.J. Thomson's experiment involved the motion of an electron beam in mutually perpendicular electric and magnetic fields. By varying the strength of the fields, Thomson was able to determine the charge-to-mass ratio of the electron. This value was found to be -1.76 x 10^11 C/kg, providing the first experimental evidence for the existence of the negatively charged electron. This experiment did not directly determine the mass or charge of an electron, the Earth's magnetic field, or Avogadro's number.

Question 8

A static magnetic field CANNOT:

Accepted Answer

A static magnetic field cannot change the kinetic energy of a charge because it only affects the motion of the charge in a perpendicular direction to the field, causing it to move in a circular motion. The magnitude of the velocity of the charge remains constant, hence its kinetic energy does not change.

Question 9

The magnetic force on a charged particle is in the direction of its velocity if:

Accepted Answer

The magnetic force on a charged particle is always perpendicular to the direction of its velocity, according to the right-hand rule. It never acts in the direction of the particle's velocity.

Question 10

In the formula  :

Accepted Answer

The answer of In the formula  :
...

Question 11

A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube.On the way, the electrons encounter a magnetic field directed vertically downward.The spot on the screen will therefore be deflected:

Accepted Answer

The direction of deflection can be determined using the right-hand rule for magnetic forces. With the magnetic field directed downward and the electrons moving horizontally, the force (and thus the deflection) will be perpendicular to both, which means to the right when viewed from the electron source.

Question 12

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north.It will be deflected:

Accepted Answer

When a positively charged particle (like a hydrogen atom that has lost its electron) moves in a magnetic field, it experiences a force perpendicular to both its velocity and the magnetic field direction. Using the right-hand rule, with the thumb pointing east (direction of motion), and the fingers pointing north (direction of the magnetic field), the palm faces up, indicating the force (and thus deflection) is upwards.

Question 13

A uniform magnetic field is in the positive z direction.A positively charged particle is moving in the positive x direction through the field.The net force on the particle can be made zero by applying an electric field in what direction?

Accepted Answer

The answer of A uniform magnetic field is in the...

Question 14

At any point the magnetic field lines are in the direction of:

Accepted Answer

Magnetic field lines indicate the direction of the magnetic field, not the direction of force or velocity on a charge. The force on a moving charge is perpendicular to both the velocity of the charge and the magnetic field.

Question 15

A proton (charge e), traveling perpendicular to a magnetic field, experiences the same force as an alpha particle (charge 2e)which is also traveling perpendicular to the same field.The ratio of their speeds, v_proton/v_alpha is:

Accepted Answer

The force experienced by a charged particle moving in a magnetic field is given by $F = qvB$, where $q$ is the charge, $v$ is the velocity, and $B$ is the magnetic field strength. For the proton, $F_p = e \cdot v_p \cdot B$, and for the alpha particle, $F_{\alpha} = 2e \cdot v_{\alpha} \cdot B$. Given that $F_p = F_{\alpha}$, we can set the equations equal to each other: $e \cdot v_p \cdot B = 2e \cdot v_{\alpha} \cdot B$. Simplifying, we find $v_p / v_{\alpha} = 2$, meaning the proton's speed is twice that of the alpha particle.

Question 16

A charged particle is projected into a region of uniform, parallel,  and  fields.The force on the particle is:

Accepted Answer

The answer of A charged particle is projected into a...

Question 17

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials.The field direction is:

Accepted Answer

The direction of the magnetic field is determined by the direction of the velocity of a test charge when the magnetic force on it is zero because the magnetic force is given by $F = q(\mathbf{v} \times \mathbf{B})$, where $q$ is the charge, $\mathbf{v}$ is the velocity of the charge, and $\mathbf{B}$ is the magnetic field. The cross product $\mathbf{v} \times \mathbf{B}$ is zero when $\mathbf{v}$ and $\mathbf{B}$ are parallel (or antiparallel), meaning no magnetic force is exerted on the charge, indicating the direction of the magnetic field.

Question 18

An electron travels due north through a vacuum in a region of uniform magnetic field  that is also directed due north.It will:

Accepted Answer

A charged particle moving parallel or antiparallel to a uniform magnetic field experiences no net force due to magnetic field, therefore its velocity remains constant, which means it will be unaffected by the field.

Question 19

An electron is moving north in a region where the magnetic field is south.The magnetic force exerted on the electron is:

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. In this case, the electron is moving north and the magnetic field is south, so the cross product of v and B will be west. The magnetic force on the electron will therefore be west.

Question 20

An electron moves in the negative x direction, through a uniform magnetic field that is in the negative y direction.The magnetic force on the electron is:

Accepted Answer

The answer of An electron moves in the negative x...

Quiz 28: Magnetic Fields

An ion with a charge of +3.2 10^?19 C is in region where a uniform electric field of 5 F10^4.V/m is perpendicular to a uniform magnetic field of 0.8 T.If its acceleration is zero then its speed must be:

A magnetic field exerts a force on a charged particle:

An electron enters a region of uniform perpendicular and fields.It is observed that the velocity of the electron is unaffected.A possible explanation is:

Units of a magnetic field might be:

An electron and a proton are both initially moving with the same speed and in the same direction at 90˚ to the same uniform magnetic field.They experience magnetic forces, which are initially:

J.J.Thomson's experiment, involving the motion of an electron beam in mutually perpendicular and fields, gave the value of:

A static magnetic field CANNOT:

The magnetic force on a charged particle is in the direction of its velocity if:

In the formula :

A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube.On the way, the electrons encounter a magnetic field directed vertically downward.The spot on the screen will therefore be deflected:

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north.It will be deflected:

A uniform magnetic field is in the positive z direction.A positively charged particle is moving in the positive x direction through the field.The net force on the particle can be made zero by applying an electric field in what direction?

At any point the magnetic field lines are in the direction of:

A proton (charge e) , traveling perpendicular to a magnetic field, experiences the same force as an alpha particle (charge 2e) which is also traveling perpendicular to the same field.The ratio of their speeds, v_proton/v_alpha is:

A charged particle is projected into a region of uniform, parallel, and fields.The force on the particle is:

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials.The field direction is:

An electron travels due north through a vacuum in a region of uniform magnetic field that is also directed due north.It will:

An electron is moving north in a region where the magnetic field is south.The magnetic force exerted on the electron is:

An electron moves in the negative x direction, through a uniform magnetic field that is in the negative y direction.The magnetic force on the electron is:

Quiz 28: Magnetic Fields

An ion with a charge of +3.2 *10?19 C is in region where a uniform electric field of 5 F*104.V/m is perpendicular to a uniform magnetic field of 0.8 T.If its acceleration is zero then its speed must be:

A magnetic field exerts a force on a charged particle:

An electron enters a region of uniform perpendicular and fields.It is observed that the velocity of the electron is unaffected.A possible explanation is:

Units of a magnetic field might be:

An electron and a proton are both initially moving with the same speed and in the same direction at 90˚ to the same uniform magnetic field.They experience magnetic forces, which are initially:

J.J.Thomson's experiment, involving the motion of an electron beam in mutually perpendicular and fields, gave the value of:

A static magnetic field CANNOT:

The magnetic force on a charged particle is in the direction of its velocity if:

In the formula :

A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube.On the way, the electrons encounter a magnetic field directed vertically downward.The spot on the screen will therefore be deflected:

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north.It will be deflected:

A uniform magnetic field is in the positive z direction.A positively charged particle is moving in the positive x direction through the field.The net force on the particle can be made zero by applying an electric field in what direction?

At any point the magnetic field lines are in the direction of:

A proton (charge e) , traveling perpendicular to a magnetic field, experiences the same force as an alpha particle (charge 2e) which is also traveling perpendicular to the same field.The ratio of their speeds, vproton/valpha is:

A charged particle is projected into a region of uniform, parallel, and fields.The force on the particle is:

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials.The field direction is:

An electron travels due north through a vacuum in a region of uniform magnetic field that is also directed due north.It will:

An electron is moving north in a region where the magnetic field is south.The magnetic force exerted on the electron is:

An electron moves in the negative x direction, through a uniform magnetic field that is in the negative y direction.The magnetic force on the electron is:

An ion with a charge of +3.2 10^?19 C is in region where a uniform electric field of 5 F10^4.V/m is perpendicular to a uniform magnetic field of 0.8 T.If its acceleration is zero then its speed must be:

A proton (charge e) , traveling perpendicular to a magnetic field, experiences the same force as an alpha particle (charge 2e) which is also traveling perpendicular to the same field.The ratio of their speeds, v_proton/v_alpha is: