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Electrostatics
1. Identify each of the following as positive, negative or neutral.
a. Proton _______
b. Electron ___________
c. Neutron _________
2. What is the value of the elementary charge? What particles have this charge?
a. 1.6 x 10-19 Coulombs
Electrons only
-19
b. -1.6 x 10 Coulombs
Protons only
c. ±1.6 x 10-19 Coulombs
Electrons and Protons
3. What does it mean to make the statement: An object is “charged”?
a. It has gained protons
b. It has gained electrons
c. It has an imbalance of electrons and protons
d. The number of neutrons is changed
4. The law of conservation of charge states:
a. Any object can gain a charge
b. The charge gained by one object is equal to the charge lost by another within a
“closed system”
c. Charge on an object is always positive
5. Materials that transfer and redistribute charge easily are
a. Conductors
b. Insulators
6. Is it easier to build up a charge on something that is an insulator or a conductor? Why?
7. Describe the following methods of charge transfer.
a. Conduction –
b. Friction –
c. Induction –
8. A balloon is rubbed against a piece of fur. It gains a net positive charge.
a. Explain the method of charging that occurred.
b. What did the balloon lose or gain to become positively charged?
9. What is an example of a static discharge?
10. Draw the electric field diagram for a positive charge.
11. Draw the electric field diagram for a negative charge.
12. Draw the electric field diagram for a positive charge and a negative charge placed near
each other.
13. Using the diagrams below, determine whether the charges are equal. Explain how you
know.
14. Coulomb’s Law is given in the following equation:
Force is _______________proportional to charge. As
charge increases, force increases
Force is _______________ proportional to distance. As
the distance between to charges increases, the force
_________________.
k = 9.0 x 109 N*m2/C2 . The purpose of the constant is
to “convert” the units from C2/m2 to Newtons
15. Given this law, which of the following statements are true? (Choose more than one)
a. If Q1 increases from a value of 1 to a value of 2, force would double
b. If the radius doubled, the force would increase by 4
c. If the radius doubled, the force would be ¼ as strong
d. If the radius tripled, the force would triple
e. If the radius tripled the force would be 1/9 of the original force
f. If both charges doubled, the force would double.
12. An object with a charge of +3 C is separated from an object with a charge of -2 C by a
distance of 0.3 m.
a. Is the electric force going to be attractive or repulsive?
b. Find the electric force using Coulomb’s Law.