Consider a wire under tension, fixed at both ends. Which of the following correctly depicts the standing waves at maximum displacement for the lowest three frequency waves?

A positive charge moving with the velocity shown in green (in the - x direction) experiences a force as shown in pink (in the + y direction) due to a magnetic field.

What is the direction of the magnetic field?

What is the code for this week's quiz?

A wire with a current of 20mA is in a magnetic field with strength 0.6T. If the current points in the negative y direction (downward) and the magnetic field points in the positive x direction (right), what is the size and direction of the force the wire experiences.

The magnetic field of a wire with current I and at a distance d away is measured to be B_0.  If I double the current (so the current is now 2I) and move to be three times as far away (so the distance is now 3d), what is the new magnetic field in terms of B_0. ?

Question 4 d)

In

some experiments, scientists want to make sure that the charged

particles entering the experiment (e.g. a beam) have the same velocity.

For this, they can use a velocity selector, which has a region of

uniform electric and magnetic fields that are perpendicular to each

other and perpendicular to the motion of the charged particles. Both the

electric and magnetic fields exert a force on the charged particles. If

a particle has precisely the right velocity, the two forces exactly

cancel and the particle is not deflected.

Equating the forces due to the electric field and the magnetic field gives the following equation:

Solving for velocity, we get:

A

particle moving at this velocity will pass through the region of

uniform fields with no deflection, as shown below. For higher or lower

velocities than this, the particles will feel a net force and will be

deflected. A slit at the end of the region allows on the particles with

the correct velocity to pass.

Question 4 a)

In

some experiments, scientists want to make sure that the charged

particles entering the experiment (e.g. a beam) have the same velocity.

For this, they can use a velocity selector, which has a region of

uniform electric and magnetic fields that are perpendicular to each

other and perpendicular to the motion of the charged particles. Both the

electric and magnetic fields exert a force on the charged particles. If

a particle has precisely the right velocity, the two forces exactly

cancel and the particle is not deflected.

Equating the forces due to the electric field and the magnetic field gives the following equation:

Solving for velocity, we get:

A

particle moving at this velocity will pass through the region of

uniform fields with no deflection, as shown below. For higher or lower

velocities than this, the particles will feel a net force and will be

deflected. A slit at the end of the region allows on the particles with

the correct velocity to pass.

Suppose a particle with twice the velocity of the particle above enters the velocity selector. The path of this particle will curve:

Question 4 b)

In

some experiments, scientists want to make sure that the charged

particles entering the experiment (e.g. a beam) have the same velocity.

For this, they can use a velocity selector, which has a region of

uniform electric and magnetic fields that are perpendicular to each

other and perpendicular to the motion of the charged particles. Both the

electric and magnetic fields exert a force on the charged particles. If

a particle has precisely the right velocity, the two forces exactly

cancel and the particle is not deflected.

Equating the forces due to the electric field and the magnetic field gives the following equation:

Solving for velocity, we get:

A

particle moving at this velocity will pass through the region of

uniform fields with no deflection, as shown below. For higher or lower

velocities than this, the particles will feel a net force and will be

deflected. A slit at the end of the region allows on the particles with

the correct velocity to pass.

True or False?

The kinetic energy of the particle in the above figure increases as it traverses the velocity selector.

Question 3 d)

A

small positive charge

Question 3 c)

A

small positive charge