Download Electric Fields Class Exercisesl

Electric Fields Class Exercises
AP Physics
1. There are two ways that we can visualize an electric field: as field vectors or field lines.
a) Draw the field vectors around a positive point
b) Draw the field lines around a negative point
charge
charge
c) How do the field vectors show the strength of
the electric field at different points?
d) How do field lines show the strength of the
electric field at different points?
2. A 0.9 C test charge is dropped in an electric
field where it feels a force of 1.5 N. How strong is
the electric field at the test charge’s location?
8. A 75 nC test charge is placed in an electric
field where it feels a force of 0.028 N. How
strong is the electric field encountered by the test
charge?
3. If a 0.5 mC test charge is placed in a 50,000
N/C electric field, how much electric force will it
experience?
10. How strong is the electric force on a 30 C
test charge placed in a 750,000 N/C electric field?
4. Let’s consider a situation where we have a point charge q creating an electric field around itself.
How strong is that field at different locations around q? [Is there a way we could calculate the strength
of the field without constantly measuring it with a test charge? Hint: How strong will the force on a test
charge qt placed a distance d away from the point charge be?]
5. Point P is 30 cm to the right of a +5 C point charge.
a) What is the electric field at point P?
b) What force would a 30 nC test charge feel if it
were placed at point P?
c) What force would a 70 nC test charge feel if it
were placed at point P?
6. Point H is 5 m to the left of a –0.9 mC point charge.
a) What is the electric field at point H?
b) What force would act on a 0.6 mC test charge
at point H?
c) What force would act on a -0.4 mC test charge
at point H?
7. Point W is 25 cm to the right of a 30 C point charge and 18 cm to the left of a -20 C point charge.
What is the net electric field at point W?
8. Point X is 5 m west of a –3.9 C point charge and 4 m north of 5.8 C point charge. What is the net
electric field at point X?
9. For an experiment, a group of physicists want a net electric field of 1,350,000 N/C at point G. They
have already set up a +65 C point charge 70 cm to the south of point G and a +50 C point charge 1.5
m to the east. The final point charge will be set 1.0 m to the west of point G.
a) In which direction will the net field point?
b) How much charge should they set at the final location?
10. While point charges are most common, it will be convenient to have a situation where the strength
of the electric field is constant (it does not vary as you move around).
a) What type of arrangement can produce a constant electric field?
b) What does the field line
How does it work?
diagram look like for a
constant electric field?
c) How can you calculate the strength of the constant electric field?
11. A set of square parallel plates, 20 cm on a side and 3 cm apart, is charged so that the top plate has
13 C of charge and the bottom plate has –13 C of charge.
a) What is the electric field between the plates?
b) What force would be exerted on a –1.9 C test charge placed between the plates?
12. A +90 nC test charge that is placed between two parallel plates experiences an upward electric force
of 3.0 N.
a) What is the electric field between the two plates?
b) If the plates are both 10 cm by 15 cm rectangles that are 2 cm apart, what is the charge on each plate?