Download HOMEWORK – II (Due to March 6th, 2012) Chapter 22 Electrostatics

HOMEWORK – II
(Due to March 6th, 2012)
Chapter 22 Electrostatics
22.1 Questions About Electrostatics
1) Which force binds atoms together to form molecules?
A) gravitational
B) nuclear
C) electrical
D) centripetal
E) none of these
2) The fundamental force underlying all chemical reactions is
A) gravitational.
B) nuclear.
C) centripetal.
D) electrical.
E) None of the above choices are correct.
3) In an electrically neutral atom the number of protons in the nucleus is equal to the number of
A) electrons that surround the nucleus.
B) neutrons in the nucleus.
C) Choices A and B are both correct.
D) Choices A and B are both incorrect.
4) A positive ion has more
A) electrons than neutrons.
B) electrons than protons.
C) protons than electrons.
D) protons than neutrons.
E) neutrons than protons.
5) Strip electrons from an atom and the atom becomes a
A) positive ion.
B) negative ion.
C) different element.
D) molecule.
6) To say that electric charge is quantized is to say that the charge on an object
A) may occur in an infinite variety of quantities.
B) is a whole-number multiple of the charge of one electron.
C) will interact with neighboring electric charges.
D) can be neither created nor destroyed.
E) is sometimes positive.
7) To say that electric charge is conserved is to say that electric charge
A) may occur in an infinite variety of quantities.
B) is a whole number multiple of the charge of one electron.
C) will interact with neighboring electric charges.
D) can be neither created nor destroyed.
E) is sometimes negative.
8) The unit of electric charge, the coulomb, is the charge on
A) one electron.
B) a specific large number of electrons.
C) a neutron.
D) a specific number of neutrons.
E) a quark.
9) A main difference between gravitational and electric forces is that electrical forces
A) attract.
B) repel or attract.
C) obey the inverse-square law.
D) act over shorter distances.
E) are weaker.
10) The electrical force between charges is strongest when the charges are
A) close together.
B) far apart.
C) The electric force is constant everywhere.
11) The electrical force between charges depends only on the charges'
A) magnitude.
B) separation distance.
C) magnitude and separation distance.
D) None of the above choices are correct.
12) A transistor is an example of a
A) resistor.
B) superconductor.
C) semiconductor.
D) dry cell.
E) transmitter.
13) Superconductors are noted for their
A) high electric resistance.
B) low electric resistance.
C) absence of electric resistance.
D) low cost.
E) bright colors.
14) Rub electrons from your hair with a comb and the comb becomes
A) negatively charged.
B) positively charged.
C) discharged.
15) An electron and a proton
A) attract each other.
B) repel each other.
C) neither attract nor repel each other.
16) Two protons attract each other gravitationally and repel each other electrically. By far the
greater force is
A) the gravitational attraction.
B) the electrical repulsion.
C) neither – the forces are the same.
17) The primary purpose of a lightning rod is to
A) attract lightning and guide it to the ground.
B) discharge the structure to which it is attached.
C) cancel the electric field within the structure to which it is attached.
D) induce a charge opposite to that of charged clouds overhead.
18) To say that an object is electrically polarized is to say
A) it is electrically charged.
B) its charges have been rearranged.
C) its internal electric field is zero.
D) it is only partially conducting.
E) it is to some degree magnetic.
Figure 22-A
19) A balloon will stick to a wooden wall if the balloon is charged
A) negatively.
B) positively.
C) either positively or negatively.
D) None of the above choices are correct.
20) When a car is struck by lightning, the resulting electric field inside the car is
A) normally huge, but for a brief time.
B) normally huge for a time longer than the lightning stroke itself.
C) small enough to be safe for an occupant inside.
D) zero.
21) Electric potential, measured in volts, is the ratio of electric energy to amount of electric
A) current.
B) resistance.
C) charge.
D) voltage.
E) None of the above choices are correct.
22) The electric field inside the dome of a Van de Graaff generator
A) depends on the amount of charge the outside of dome.
B) depends on the volume of the dome
C) Choices A and B are both correct.
D) None of the above choices are correct.
23) An uncharged pith ball is suspended by a nylon fiber. When a negatively charged rubber rod
is brought nearby, without touching it, the pith ball
A) becomes charged by induction.
B) becomes polarized.
C) is repelled by the rod.
D) is unaffected.
E) None of the above choices are correct.
24) The net charge on a charged capacitor depends on
A) the area of the capacitor plates.
B) the distance between the capacitor plates.
C) the medium between the capacitor plates.
D) All of the above choices are correct.
E) None of the above choices are correct – the net charge is zero.
25) After a capacitor is fully charged, the total number of electrons it contains
A) is slightly greater.
B) is much greater.
C) is slightly less.
D) is much less.
E) remains unchanged.
26) When the distance between two charges is halved, the electrical force between the charges
A) quadruples.
B) doubles.
C) halves.
D) is reduced by 1/4.
E) None of the above choices are correct.
27) Particle A has twice the charge of nearby particle B. Compared to the force on Particle A, the
force on Particle B is
A) four times as much.
B) twice as much.
C) the same.
D) half as much.
E) None of the above choices are correct.
28) If you comb your hair and the comb becomes positively charged, then your hair becomes
A) positively charged.
B) negatively charged.
C) uncharged.
29) To say that electric charge is conserved means that no case has ever been found where the
A) total charge on an object has changed.
B) net amount of negative charges on an object is unbalanced by positive charge on another
object.
C) total amount of charge on an object has increased.
D) net charge has been created or destroyed.
E) None of the above choices are correct.
30) A difference between electric forces and gravitational forces is that gravitational forces are
not affected by
A) separation distance.
B) repulsive interaction.
C) the inverse-square law.
D) infinite range.
E) None of the above choices are correct.
31) A conductor differs from an insulator in that a conductor
A) has more electrons than protons.
B) has more protons than electrons.
C) has more energy than an insulator.
D) has faster moving molecules.
E) none of these
32) A negatively charged rod is held near a metal can that rests on a dry wood table. If you touch
the opposite side of the can momentarily with your finger, the can is then
A) positively charged.
B) negatively charged.
C) partially discharged.
D) completely discharged.
E) discharged only on the side touched.
33) Every proton in the universe is surrounded by its own
A) electric field and gravitational field.
B) gravitational field.
C) electric field
D) None of the above choices are correct.
34) The direction of an electric field is the direction of the force that the field would exert on
A) a neutral test charge.
B) an electron.
C) an atom.
D) a proton.
E) a molecule.
35) The electric field around an isolated electron has a certain strength 1 cm from the electron.
The electric field strength 2 cm from the electron is
A) half as much.
B) the same.
C) twice as much.
D) four times as much.
E) None of the above choices are correct.
36) If you use 10 J of work to push a coulomb of charge into an electric field, its voltage with
respect to its starting position is
A) less than 10 V.
B) 10 V.
C) more then 10 V.
D) None of the above choices are correct.
37) Assume that 10 J of work is needed to push a charge, at rest, into an electric field. After the
charge is released there, it flies back to its starting position and its kinetic energy there will be
A) zero.
B) 5 J.
C) 10 J.
D) more than 10 J.
E) impossible to predict without additional information.
38) An electroscope is charged positively as shown by foil leaves that stand apart. As a negative
charge is brought close to the electroscope, the leaves
A) fall closer together.
B) spread apart further.
C) do not move.
39) Charge carriers in a metal are electrons rather than protons because electrons are
A) negative.
B) smaller.
C) loosely bound.
D) all of these
E) none of these
40) In the unlikely case of a lightning strike, it is worse to be inside a building framed with
A) steel.
B) iron.
C) aluminum.
D) wood.
41) A highly charged child's balloon is not dangerous because
A) rubber is not a good conductor of electricity.
B) its outside surface is positively charged.
C) the potential difference between the balloon and the child's hand is very small.
D) None of the above choices are correct.
42) Normally a small party balloon charged to several thousand volts will have a relatively small
amount of
A) charge and energy.
B) energy.
C) charge.
D) neither charge nor energy.
43) You can touch a 100,000-volt Van de Graaff generator with little harm because although the
voltage is high, the relatively small amount of charge means there is a relatively small amount of
A) energy.
B) electric field.
C) polarization.
D) conduction.
44) Two charges separated by one meter exert 1-N forces on each other. If the charges are
pushed to 1/4 meter separation, the force on each charge will be
A) 1 N.
B) 2 N.
C) 4 N.
D) 8 N.
E) 16 N.
45) Two charges separated by one meter exert 1-N forces on each other. If the charges are pulled
to 3-m separation distance, the force on each charge will be
A) 0.33 N.
B) 0.11 N.
C) 0 N.
D) 3 N.
E) 9 N.
46) Two charges separated by one meter exert 1-N forces on each other. If the magnitude of each
charge is doubled, the force on each charge is
A) 1 N.
B) 2 N.
C) 4 N.
D) 8 N.
E) None of the above choices are correct.
47) The electrical force on a 2-C charge is 60 N. What is the value of the electric field at the
place where the charge is located?
A) 20 N/C
B) 30 N/C
C) 60 N/C
D) 120 N/C
E) 240 N/C
48) Two charged particles repel each other with a force F. If the charge of one of the particles is
doubled and the distance between them is also doubled, then the force will be
A) F.
B) 2 F.
C) F/2.
D) F/4.
E) none of these
49) Two charged particles attract each other with a force F. If the charges of both particles are
doubled, and the distance between them also doubled, then the force of attraction will be
A) F.
B) 2 F.
C) F/2.
D) F/4.
E) none of these
50) When a single charge q is placed on one corner of a square, the electric field at the center of
the square is F/q. If three other equal charges are placed on the other corners, the electric field at
the center of the square due to these four equal charges is
A) F/q.
B) 4F/q.
C) F/(2q).
D) F/(4q).
E) None of the above choices are correct.
51) When a single charge q is placed at one corner of a square, the electric field at the center of
the square is F/q. If two other equal charges are placed at the adjacent corners of the square, the
electric field at the center of the square due to these three equal charges is
A) F/q.
B) 4F/q.
C) F/(2q).
D) F/(4q).
E) None of the above choices are correct.
52) An electron is pushed into an electric field where it acquires a 1-V electrical potential. If two
electrons are pushed the same distance into the same electric field, the electrical potential of the
two electrons is
A) 0.25 V.
B) 0.5 V.
C) 1 V.
D) 2 V.
E) 4 V.
53) The electric field inside an uncharged metal ball is zero. If the ball is negatively charged, the
electric field inside the ball is then
A) less than zero.
B) zero.
C) greater than zero.
54) Two charged particles held close to each other are released. As they move, the force on each
particle increases. Therefore, the particles must have
A) the same sign.
B) opposite signs.
C) the same mass.
D) the same size.
E) impossible to answer without additional information
55) Two charged particles held close to each other are released. As the particles move, the
velocity of each increases. Therefore, their charges have
A) the same sign.
B) opposite signs.
C) either the same or opposite signs.
D) impossible to answer without additional information
56) A positive charge and a negative charge held near each other are released. As they move, the
force on each particle
A) increases.
B) decreases.
C) stays the same.
57) Two charged particles held near each other are released. As they move, the acceleration of
each decreases. Therefore, the particles have
A) the same sign.
B) opposite signs.
C) not enough information given
58) A proton and an electron are placed in an electric field. Which undergoes the greater
acceleration?
A) electron
B) proton
C) Both accelerate equally.
D) Neither accelerates.