South Pasadena · AP Physics Name______Period___
16 · Electrostatics Practice Test
· ELECTRIC CHARGES ·
1. An object possessing an excess of 6.0 x 106 electrons, has what net charge?
2. An alpha particle consists of two protons and two neutrons in the nucleus and no electrons outside the nucleus. What is the net charge of an alpha particle in Coulombs?
a) 1.25 x 1019 C c) 6.40 x 10‒19 C
b) 2.00 C d) 3.20 x 10‒19 C
3. If an object has a net negative charge of 4 Coulombs, the object possesses
a) 6.3 x 1018 more electrons than protons.
b) 2.5 x 1019 more electrons than protons.
c) 6.3 x 1018 more protons than electrons.
d) 2.5 x 1019 more protons than electrons.
4. Which quantity of excess electric charge could be found on an object?
a) 6.25 x 10‒19 C c) 6.25 elementary charges
b) 4.80 x 10‒19 C d) 1.6 elementary charges
5. When a neutral magnesium atom loses two electrons, it becomes a +2 charged ion. What is this net electrical charge in Coulombs?
a) ‒3.2 x 10‒19 C c) +1.6 x 10‒19 C
b) ‒1.6 x 10‒19 C d) +3.20 x 10‒19 C
· CHARGING BY CONDUCTION ·
6. If a conductor carrying a net charge of 8 elementary charges is brought into contact with an identical conductor with no net charge, what will be the charge on each conductor after they are separated?
Each conductor will have a charge of ______?
7. What would be the net charge (in Coulombs) on each conductor in the previous question, after they are separated?
8. Metal sphere A has a charge of ‒2 units and an identical metal sphere B, has a charge of ‒4 units. If the spheres are brought into contact with each other and then separated, the charge on sphere B will be
a) 0 units c) ‒ 3 units
b) ‒ 2 units d) + 4 units
9.
9. Compared to insulators, metals are better conductors of electricity because metals contain more free
a) Protons c) positive ions
b) Electrons d) negative ions
10. Separation of the leaves of an electroscope when an object is touched to the electroscope’s conducting rod could indicate (choose all that apply):
a) The object is neutral.
b) The object is negatively charged.
c) The object is positively charged.
d) The object is an insulator.
· CHARGING BY INDUCTION ·
11. A positively charged glass rod attracts object X. The net charge of object X
a) May be zero or negative.
b) May be zero or positive.
c) Must be negative.
d) Must be positive.
12. The diagram below shows three neutral metal spheres, x, y, and z, in contact and on insulating stands.
x y z
Which diagram below best represents the charge distribution on the spheres when a positively charged rod is brought near sphere x, but does not touch it?
a) (1) c) (3)
b) (2) d) (4)
· COULOMBS LAW ·
13. Three protons are separated from a single electron by a distance of 1.0 x 10‒6 m. Find the electrostatic force between them. Is this force attractive or repulsive?
14. A distance of 1.0 m separates the centers of two small charged spheres. The spheres exert gravitational force, F g and electrostatic force, Fe on each other. If the distance between the sphere’s centers is increased to 3.0 m, the gravitational force and electrostatic force, respectively, may be represented as
a) F g/9 and Fe/9
b) F g/3 and Fe/3
c) 3F g and 3Fe
d) 9F g and 9Fe
15. The centers of two small charged particles are separated by a distance of 1.2 x 10‒4 meters. The charges on the particles are + 8.0 x 10‒19 C and
+ 4.8 x 10‒19 C, respectively.
a) Calculate the magnitude of the electrostatic force between these two particles.
b) Sketch a graph showing the relationship between the magnitude of the electrostatic force between the two charged particles and the distance between the centers of the particles.
Force
Distance
Chapter 16 Electrostatics Practice Test ANSWERS
Some Notes and more questions:
All observed forces that we have studied can be consolidated into four fundamental forces.
They are, from the strongest force to the weakest force:
1. Strong Nuclear Force, which holds protons and neutrons together in the nucleus.
2. Electromagnetic Force, which is the electrical (electrostatic) and magnetic attraction and repulsion forces.
3. Weak Nuclear Force which is responsible for radioactive beta decay and
4. Gravitational Force which is the attractive force between any two objects with mass.
Question 1: The particles in a nucleus are held together primarily by the
a) Strong force
b) Gravitational force
c) Electrostatic force
d) Magnetic force
Answer is a)
Question 2: Which statement is true of the strong nuclear force?
a) It acts over very great distances
b) It holds protons and neutrons together.
c) It is much weaker than gravitational forces.
d) It repels neutral charges.
Answer is b)
Question 3: The strong force is the force of
a) Repulsion between protons
b) Attraction between protons and electrons.
c) Repulsion between nucleons.
d) Attraction between nucleons
(nucleons are the particles in the nucleus)
Answer is d)
• ANSWERS •
1. / ‒9.6 x 10-13 C / 6. / 4 elementary charges / 11. / A2. / D / 7. / 6.4 x 10‒19 C / 12. / D
3. / A / 8. / C / 13. / F = ‒ 6.9 x 10‒16 N
attractive
4. / B / 9. / B / 14. / A
5. / D / 10. / B & C / 15.a) / Fe = 2.4 x 10‒19 N
15. b) / See below
15. b)
Force
Distance
S