Electrostatics Review
1. To say that electric charge is conserved means that no case has ever been found where
a. the total amount of charge on an object has increased.
b. one object has more charge than another object.
c. the total charge on an object has changed.
d. net charge has been created or destroyed.
e. none of the above
2. If you comb your hair and the comb becomes positively charged, your hair becomes
a. uncharged.
b. positively charged.
c. negatively charged.
3. An area with excess electrons has a net _____ charge; an area with a deficit of electrons has a net _____ charge.
a. negative, positive
c. positive, neutral
b. positive, negative
d. negative, neutral
4. A positive ion has
a. more electrons than protons.
b. more protons than electrons.
c. a +1 charge always.
d. one proton.
5. What happens when a rubber rod is rubbed with a piece of fur, giving it a negative charge?
a. Protons are removed from the rod.
c. The fur is also negatively charged.
b. Electrons are added to the rod.
d. The fur is left neutral.
6. Electric charge is
a. found only in a conductor.
c. found only in insulators.
b. conserved.
d. not conserved.
7. Which of the following transfers electrons by friction most easily?
a. nonconductors
c. semiconductors
b. conductors
d. insulators
8. Electrical forces between charges are strongest when the charges are
a. far apart.
b. close together.
c. The electrical force is constant everywhere.
9. When two bodies are charged, the total charge before and after charging remains the same because of:
a. quantization of charges
c. law of induction
b. conservation of charges
d. Coulomb’s law
10. A/An _____ is a material in which charges will not move easily, whereas a/an _____ is a material that allows charges to move
about easily.
a. conductor, insulator
c. electroscope, conductor
b. insulator, conductor
d. insulator, electroscope
11. Metals contain _____ electrons; rubber has _____ electrons.
a. bound, free
c. excess, insufficient
b. free, bound
d. insufficient, excess
12. A/An _____ is a unit equal to one joule per coulomb.
a. volt
c. capacitance
b. capacitor
d. electric field line
13. Electric field lines are directed _____ positive charges and _____ negative charges.
a. away from, toward
c. parallel to, perpendicular to
b. toward, away from
d. perpendicular to, parallel to
14. The direction of electric field lines shows the
a. direction of the force on a test positive charge.
b. size of the field.
c. strength of the field.
d. all of the above
15. Which of the following is true for the direction of an electric field?
a. It is same as the direction of the force exerted on a negative test charge.
b. It is opposite to the direction of the force exerted on a positive test charge.
c. It is same as the direction of the force exerted on a positive test charge.
d. It is opposite to the direction of the force exerted on a neutral test charge.
16. Electrical potential energy is the energy a charged object has because of its
a. momentum.
b. location.
c. mass.
d. motion.
e. volume.
17. If two negative charges are held close together and then released, the charges will
a. accelerate toward each other.
b. accelerate away from each other.
c. not move.
d. move at a constant speed away from each other.
18. A small, positively charged object near a positively charged sphere is moved closer to the sphere. The electrical potential energy
of the small object
a. stays the same.
b. decreases.
c. increases.
19. A volt is a unit of
a. charge.
b. electric potential.
c. energy.
d. work.
e. current.
20. The electric field outside a Van de Graaff generator may be enormous, while at the center of the spherical dome, the electric field
is
a. even more enormous.
b. almost as enormous.
c. zero.
21. Electric field lines between two oppositely charged parallel metal plates will be
a. straight lines, randomly spaced.
b. straight lines, evenly spaced.
c. curved lines grouped together in small bunches.
d. curved lines, evenly spaced.
e. curved lines, randomly spaced.
22. In a capacitor, the two plates have _____ charges.
a. equal and opposite
c. both positive
b. equal and similar
d. both negative
23. Charge build up between the plates of a capacitor stops when
a. there is no net charge on the plates.
b. unequal amounts of charge accumulate on the plate.
c. the potential difference between the plates is equal to the potential difference between the terminals of the battery.
d. the charge on both plates is the same.
24. When a capacitor discharges,
a. it must be attached to a battery.
b. charges move back from one plate to another through the circuit until both plates are uncharged.
c. charges move from one plate to another until equal and opposite charges accumulate on the plates.
d. it cannot be connected to a material that conducts.
25. When comparing the net charge of a charged capacitor with the net charge of the same capacitor when it is uncharged, the net
charge is
a. greater in the charged capacitor.
b. less in the charged capacitor.
c. equal in both capacitors.
d. greater or less in the charged capacitor, but never equal
26. 1.9 x 1013 electrons
27. 0.42-m
28. a. 92.5-N to the Left
b. 188.9-M to the Right
c. 96.4-N to the Left
29. 1-J
30. +1.3 x 10-17 C
31. ΔV= 3375-J so
32. 2.025 x 10-5 J
33. 7.55 x 10-11-C
34. 3.18 x 108 -m2
Vtotal = 6625V