All AP Physics 2 Resources
Example Questions
Example Question #21 : Electricity And Magnetism
Mass of electron:
An electron enters a magnetic field at velocity and experiences a force of . Determine the magnetic field.
Use the magnetic force equation:
Plug in known values and solve for
Example Question #11 : Magnetic Force
What direction of force would a negative charge at location moving left experience due to the magnetic field?
Into the screen
To the left
Out of the screen
Up
Down, towards the bottom of the screen
Down, towards the bottom of the screen
Using the right hand rule for a current carrying wire shows that the magnetic field is pointing out of the screen. Using the right hand rule for magnetic force on a negatively charged particle shows the force acting downward.
Example Question #27 : Electricity And Magnetism
Which of the following conditions is not needed in order for a particle to experience a magnetic force?
The particle must be moving in a direction that is neither parallel or antiparallel to the direction of an external magnetic field
All of these conditions are needed for a magnetic force to act on a particle
The particle must have a charge
There must be a current
The particle must be of a certain size
The particle must be of a certain size
In this question, we're asked to determine which answer choice falsely represents a necessary condition for a magnetic force to act on a particle.
To answer this, it is useful to look at the equation for magnetic force.
What this equation shows is that the magnetic force on a particle is dependent upon that particle's charge, its velocity, and on the strength of the magnetic field. Already we can rule out a few of the answer choices.
Additionally, this equation also shows that cannot be equal to zero. What this means is that the particle's direction of motion cannot be along the magnetic field lines. In other words, the particle cannot be travelling in a direction that is parallel or antiparallel with the magnetic field.
Lastly, we can see that no where in the above equation is there a variable for the size of the particle. Thus, size is not a requirement for a particle to experience a magnetic force.
Example Question #23 : Electricity And Magnetism
Two electrons are traveling parallel to each other apart. The distance between them is perpendicular to their motion. One of them is on a track that prevents it from moving side to side. The other one is able to movie in all directions. At what velocity would the magnetic attractive force equal the repulsive electric force?
None of these
Using
Where
is the charge limited to traveling in a single dimension
is the free charge
is the distance between the charges
is the velocity of the first charge
is the velocity of the second charge
is the value of the first charge
is the value of the second charge
and are equivalent as the charges are running parallel to each other
Combining equations:
Solving for
Plugging in values:
Example Question #24 : Electricity And Magnetism
A proton is traveling parallel to a wire in the same direction as the conventional current. The proton is traveling at . The current in the wire is . The proton and the wire are apart. Determine the magnetic force on the proton.
None of these
Finding the magnetic field at the location of the proton.
Converting to and plugging in values
Using
Example Question #11 : Magnetic Force
A circuit contains a battery and a resistor in series. Determine the magnitude of the magnetic force outside of the loop away from the wire on an electron that is stationary.
None of these
None of these
Since the electron is stationary, there will be no magnetic force, as magnetic force requires the particle to be both charged and to be moving.
Example Question #11 : Magnetic Force
A circuit contains a battery and a resistor in series. Determine the magnitude of the magnetic force outside of the loop away from the wire on an electron that is moving parallel to the magnetic field.
None of these
None of these
Magnetic fields do not affect charges that are moving parallel to them.
Thus, the magnetic force will be at a maximum when moving perpendicular to the field, and at zero when moving parallel to the field.
Example Question #671 : Ap Physics 2
A scientist wishes for an electron to move in a circle of radius at . Determine the necessary magnetic field to make this happen.
None of these
The centripetal force will need to be equal to the magnetic force.
Solving for
Converting:
Plugging in values:
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