CHAPTER 1
ELECTRIC CHARGE AND COULOMB’S LAW
MULTIPLE CHOICE
1.
Electromagnetism: A Preview
Electric Charge
Electric charges A and B are attracted to each other. Electric charges B and C
repel each other. If A and C are held close together they will
(A) attract.
(B) repel.
(C) not affect each other
(D) More information is needed to
answer.
2.
Electric charges A and B are attracted to each other. Electric charges B and C
are also attracted to each other. If A and C are held close together they will
(A) attract.
(B) repel.
(C) not affect each other
(D) More information is needed to
answer.
3.
Electric charges A and B repel each other. Electric charges B and C also repel
each other. If A and C are held close together they will
(A) attract.
(B) repel.
(C) not affect each other
(D) More information is needed to
answer.
Conductors and Insulators
4.
If an object made of substance A rubs an object made of substance B, then A
becomes positively charges and B becomes negatively charged. If, however,
an object made of substance A is rubbed against an object made of substance
C, then A becomes negatively charged. What will happen if an object made of
substance B is rubbed against an object made of substance C?
(A) B becomes positively charged and C becomes positively charged.
(B) B becomes positively charged and C becomes negatively charged.
(C) B becomes negatively charged and C becomes positively charged.
(D) B becomes negatively charged and C becomes negatively charged.
5.
A positively charged rod is held near a ball suspended by an insulating thread.
The ball is seen to swing toward the charged rod. What can be concluded?
(A) The ball must have had a charge opposite to that of the rod.
(B) The ball may have been neutral originally, but it became charged when the
rod was held near it.
(C) The ball must be conductor.
(D) The ball is not positively charged, but it could be neutral.
6.
A spherical conducting ball is suspended by a grounded conducting thread. A
positively point charge is moved near the ball. The ball will
(A) be attracted to the point charge and swing toward it.
(B) be repelled from the point charge and swing away from it.
(C) not be affected by the point charge.
7.
A spherical conducting ball is suspended by an insulating thread. A positive
point charge is moved near the ball. The ball will
(A) be attracted to the point charge and swing toward it.
(B) be repelled from the point charge and swing away from it.
(C) not be affected by the point charge.
Coulomb’s Law
8.
A 3-C point charge q1 is located a distance d away from a – 6-C point charge
q2. What is the ratio F12 / F21
(A) 1/2
(C) 2
(B) 1
(D) 18
9.
Two 200-pound lead balls are separated by a distance of 1 m. Both balls have
the same positive charge q. What charge will produce an electrostatic force
between the balls that is of the same order of magnitude as the weight of one
ball?
(A) 1 × 10-14 C
(B) 1 × 10-7 C
(C) 3 × 10-4 C
(D) 2 × 10-2 C
10.
Two identical, small, conducting spheres are separated by a distance of 1 m.
The spheres originally have the same positive charge, and the force between
them is F0. Half of the charge on one sphere is then moved to the other sphere.
The force between the spheres is now
(A) F0/4.
(B) F0/2.
(C) 3F0/4.
(D) 3F0/2.
(E) 3F0.
11.
Two identical, small conducting spheres are separated by a distance of 1 m.
The spheres originally have equal but opposite charges, and the force between
them is F0. Half of the charge on one sphere is then moved to the other sphere.
The force between the spheres is now
(A) F0/4.
(B) F0/2.
(C) 3F0/4.
(D) 3F0/2.
(E) 3F0.
Continuous Charge Distributions
12.
A point charge q is located a distance a from the surface of a sphere of radius
2a. A charge Q is distributed uniformly throughout the volume of the sphere.
The magnitude of the electrostatic force between the point charge q and the
sphere is F, where
(A) F  qQ / 4 0 a2 .
(B) qQ / 4 0 a2  F  qQ / 12 0 a2.
(C) qQ / 12 0 a2  F  qQ / 20 0 a2.
(D) F  qQ / 36 0 a2.
Conservation of Change
13.
A positively charged rod is held near a neutral conducting sphere suspended
by an insulating thread. The sphere will
(A) be unaffected, because it is neutral.
(B) remain neutral, but be repelled from the rod anyway.
(C) remain neutral, but be attracted to the rod anyway.
(D) acquire a negative charge and be repelled from the rod.
(E) acquire a negative charge and be attracted to the rod.
14.
Objects A, B and C are three identical, insulated, spherical conductors.
Originally A and B both have charges of +3 mC, while C has a charge of – 6
mC. Objects A and C are allowed to touch, then they are moved apart. Then
objects B and C are allowed to touch, and they are moved apart.
(a)
If object A and B are now held near each other, they will
(A) attract.
(B) repel.
(C) have no effect on each other.
(b)
If object A and C are held near each other, they will
(A) attract.
(B) repel.
(C) have no effect on each other.