All AP Physics 2 Resources
Example Questions
Example Question #751 : Ap Physics 2
Suppose I have a uniform electric field within a parallel plate capacitor with field strength of .
Suppose the capacitor's plates are in length and the space between the plates is .
Determine the magnitude of force experienced by an individual electron placed in this field and the direction. Assume the charge of an electron is
towards the negative plate
towards the positive plate
towards the positive plate
towards the positive plate
towards the positive plate
Recall that the formula for the magnitude of force is given by:
Where is the electric field strength and is the charge.
Since the electric field strength is constant,
To determine direction, remember that electrons will move towards the positively charged plates since electrons are negatively charged.
Example Question #102 : Electricity And Magnetism
An electron is moved in a perfect circle, with a negative point charge in the center. Determine the work done by the negative point charge.
No work done
Impossible to determine
Positive work done
Infinite work done
Negative work done
No work done
There will be no work done. The point charge at the center is emitting an electric field towards itself. If the electron is moved in a circle around it, it will have moved perpendicular to the force the entire time, and thus no work has been done.
Example Question #1 : Electric Force Between Point Charges
Two charges are placed a certain distance apart such that the force that each charge experiences is 20 N. If the distance between the charges is doubled, what is the new force that each charge experiences?
There is no way to determine the new force
To solve this problem, we'll need to utilize the equation for the electric force:
We're told that the force each charge experiences is 20 N at a certain distance, but then that distance is doubled. Thus, the new electric force will be:
Example Question #2 : Electric Force Between Point Charges
What is the force experienced by a point charge away from a point charge?
The point charge experiences no force
The equation to find the force from two point charges is called Coulomb's Law.
In this equation, is force in Newtons, is the respective charge value in , is radius in meters, and is the Coulomb constant, which has a value of .
Now, we just plug in the numbers. Note: the charge values are in microcoulombs (the Greek letter , called "mu," stands for micro), which is equal to .
Therefore, the force experienced on either charge is 0.216N of force.
Example Question #1 : Electric Force Between Point Charges
You have two point charges, and , 3m away from each other. The value of is , and the force they both experience is . What is the value of ?
The equation for the force between two point charges is as follows:
We have the values for , , , and , so we just need to rearrange the equation to solve for , then plug in the values we have.
Therefore, the value for the second charge is .
Example Question #1 : Electric Force Between Point Charges
Two objects in space are placed apart. One has a charge of , the second has a charge of . What is the electric force between them?
towards each other
towards each other
away from each other
towards each other
away from each other
towards each other
Use Coloumb's law:
First, convert the charges into coulombs.
Plug in values into Coulomb's law.
Negative electric forces indicate attractive forces. Alternatively, we can reason that since one charge is positive, and the other is negative, the charges will attract.
Example Question #756 : Ap Physics 2
If charge has a value of , and charge has a value of , and the distance between their centers, , is what will be the magnitude of the force on charge ?
None of these
Using coulombs law to solve
Where:
it the first charge, in coulombs.
is the second charge, in coulombs.
is the distance between them, in meters
is the constant of
Converting into
Plugging values into coulombs law
The magnitude will be the absolute value.
Example Question #1 : Electric Force Between Point Charges
If charge has a value of , and charge has a value of , and the distance between their centers, , has a value of , what will be the force on charge ?
None of these
Using coulombs law to solve
Where:
it the first charge, in coulombs.
is the second charge, in coulombs.
is the distance between them, in meters
is the constant of
Converting into
Plugging values into coulombs law
Magnitude will be the absolute value
Example Question #757 : Ap Physics 2
Charge has a charge of
Charge has a charge of
The distance between their centers, is .
What is the magnitude of the force on due to ?
None of these
Using the electric field equation:
Where is
is charge , in
is charge , in
is the distance, in .
Convert to and plug in values:
Magnitude is equivalent to absolute value:
Example Question #3 : Electric Force Between Point Charges
Charge has a charge of
Charge has a charge of
The distance between their centers, is .
What is the magnitude of the force on due to ?
None of these
Use Coulomb's law:
Where is
is charge , in
is charge , in
is the distance, in .
Convert to and plug in values:
Magnitude is equivalent to absolute value: