Download Physics HW Weeks of April 22 and 29 Chapters 32 thru 34 (Due May

Physics HW Weeks of April 22 and 29 Chapters 32 thru 34 (Due May 1, Test May 3)
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. The charge of an electron is
a. positive.
b. negative.
c. Electrons have no charge.
2. Atomic nuclei of almost all elements consist of
a. only neutrons.
b. protons and electrons.
c. neutrons and electrons.
d. only protons.
e. protons and neutrons.
3. Two like charges
a. neutralize each other.
b. repel each other.
c. must be neutrons.
d. attract each other.
e. have no effect on each other.
4. Protons and electrons
a. attract each other.
b. repel each other.
c. do not interact.
5. The fundamental force underlying all chemical reactions is
a. electrical.
b. gravitational.
c. centripetal.
d. nuclear.
e. none of the above
6. Electrical forces between charges are strongest when the charges are
a. far apart.
b. close together.
c. The electrical force is constant everywhere.
7. Coulomb's law says that the force between any two charges depends
a. directly on the size of the charges.
b. inversely on the square of the distance between the charges.
c. both A and B
d. none of the above
8. Two charges are separated by a certain distance. If the magnitude of each charge is doubled, the force on each
charge is
a. halved.
b. doubled.
c. tripled.
d. quadrupled.
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9. When the distance between two charges is halved, the electrical force between the charges
a. doubles.
b. reduces to one fourth.
c. halves.
d. quadruples.
e. none of the above
10. The net charge of a nonionized atom
a. depends only on the number of electrons it has.
b. is zero.
c. usually cannot be determined.
d. depends only on the number of protons it has.
11. A positive ion has
a. more electrons than protons.
b. more protons than electrons.
c. a +1 charge always.
d. one proton.
12. Conservation of charge means that
a. the total amount of charge in the universe is constant.
b. no experimenter has ever seen a single charge destroyed by itself.
c. electrons by themselves can be neither created nor destroyed.
d. charge can be neither created nor destroyed.
e. all of the above
13. If you comb your hair and the comb becomes positively charged, your hair becomes
a. uncharged.
b. positively charged.
c. negatively charged.
14. 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
15. A difference between electrical forces and gravitational forces is that electrical forces include
a. infinite range.
b. repulsive interactions.
c. the inverse square law.
d. separation distance.
e. none of the above
16. The common hydrogen atom consists of
a. one electron.
b. one proton and one electron.
c. one proton.
d. two protons, one neutron, and two electrons.
e. one neutron and one electron.
____ 17. In a good insulator, electrons are usually
a. not moving at all.
b. free to move around after an impurity has been added.
c. free to move around.
d. tightly bound in place.
e. semi-free to move around.
____ 18. Charge carriers in a metal are electrons rather than protons, because electrons are
a. relatively far from a nucleus.
b. loosely bound.
c. lighter.
d. all of the above
e. none of the above
____ 19. To be safe in the unlikely case of a lightning strike, it is best to be inside a building framed with
a. steel.
b. wood.
c. either A or B.
____ 20. A negatively charged rod is brought near a metal can that rests on a wood table. You touch the opposite side
of the can momentarily with your finger. The can is then
a. positively charged.
b. negatively charged.
c. charged the same as it was.
d. uncharged.
____ 21. Lightning bolts occur between
a. clouds and the ground.
b. clouds.
c. both A and B.
____ 22. When a charged cloud passes overhead, the ground below is charged by
a. induction.
b. polarization.
c. deduction.
d. electrification.
____ 23. Bring a charged object near a conductor and then momentarily touch the conductor. This demonstrates charge
by
a. deduction.
b. polarization.
c. induction.
d. electrification.
____ 24. A rubbed balloon will stick to a wooden wall, which demonstrates charge
a. transfer.
b. potential.
c. conservation.
d. polarization.
____ 25. Electrical polarization occurs when
a. an electron is at a different location than a proton.
b. charge distribution in a neutral molecule separates.
c. the electron and the proton are on different sides of an atom.
d. an atom vibrates in a single direction.
e. none of the above
____ 26. The reason a charged balloon will stick to a wall is that
a. induced opposite charges in the wall are closer than other wall charges.
b. the rubber of the balloon simply sticks to walls.
c. electrons transfer back and forth between the wall and the balloon.
d. the charge is slightly sticky and acts like glue.
e. none of the above
____ 27. Two charged particles held close to each other are released. As they move, the force on each particle
increases. Therefore, the particles have
a. opposite signs.
b. the same sign.
c. charges that cannot be determined
____ 28. Two charged particles held close to each other are released. As the particles move, the velocity of each
increases. Therefore, the particles have
a. the same sign.
b. opposite signs.
c. charges that cannot be determined.
____ 29. A positive charge and a negative charge held near each other are released. As they move, the force on each
particle
a. increases.
b. stays the same.
c. decreases.
____ 30. Two charged particles held near each other are released. As they move, the acceleration of each decreases.
Therefore, the particles have
a. opposite signs.
b. the same sign.
c. charges that can not be determined.
____ 31. How many different kinds of force would act on a proton placed in both an electric field and a gravitational
field?
a. one.
b. none.
c. two.
____ 32. The SI unit of charge is the
a. ohm.
b. joule.
c. coulomb.
d. ampere.
e. newton.
____ 33. Particle A has twice as much charge as particle B. Compared to the force on particle A, the force on particle B
is
a. half as much.
b. two times as much.
c. four times as much.
d. the same.
e. none of the above
____ 34. The electrostatic force between two charges located 8 meters apart is 0.10 N. What will the force be between
these charges when they are located 2 meters apart?
a. 0.01 N
b. 0.03 N
c. 0.1 N
d. 0.8 N
e. 1.6 N
____ 35. A 2-C charge and a 4-C charge attract each other with 10 N of force. How much will a 2-C charge and a 12-C
charge attract each other when placed the same distance apart?
a. 5 N
b. 12 N
c. 10 N
d. 30 N
e. 60 N
____ 36. Two charges separated a distance of 1.0 meter exert a 2.0-N force on each other. If the charges are pushed to a
separation of meter, the force on each charge will be
a. 2.0 N.
b. 1.5 N.
c. 3.0 N.
d. 6.0 N.
e. 18.0 N.
____ 37. Two charges separated by a distance of 1 meter exert a 20-N force on each other. If the charges are pulled to a
2 meter separation distance, the force on each charge will be
a. 0 N.
b. 5 N.
c. 10 N.
d. 40 N.
e. 80 N.
____ 38. Two charges separated by a distance of 1 meter exert a 2-N force on each other. If the magnitude of each
charge is doubled, the force on each charge is
a. 2 N.
b. 4 N.
c. 8 N.
d. 16 N.
e. none of the above
____ 39. If you walk into a region of space and suddenly feel a force, the space is said to contain a
a. charged object.
b. force field.
c. large charge.
d. black hole.
e. heavy object.
____ 40. Every proton in the universe is surrounded by its own
a. gravitational field.
b. electric field.
c. both A and B
d. none of the above
____ 41. Suppose a hollow metal sphere has a large negative charge on it. The electric field strength inside the sphere
is
a. large and positive.
b. zero.
c. weak and negative.
d. weak and positive.
e. large and negative.
____ 42. Electrical potential energy is the energy a charged object has because of its
a. momentum.
b. location.
c. mass.
d. motion.
e. volume.
____ 43. When an electron is brought near a negatively charged sphere, its potential energy increases. The reason this
happens is that
a. two like charges go from a position far apart to a position close together.
b. negative charges repel each other.
c. work was done to bring the charges together.
d. none of the above
____ 44. Electric potential is defined as
a. electrical potential energy of a charge multiplied by the quantity of the charge.
b. electrical potential energy of a charge divided by the quantity of the charge.
c. electrical potential energy.
d. gravitational potential.
e. voltage.
____ 45. A volt is a unit of
a. charge.
b. electric potential.
c. energy.
d. work.
e. current.
____ 46. Suppose a hollow metal sphere has a large number of extra electrons on it. The extra electrons will be located
a. only on the outside surface of the sphere.
b. only on the inside surface of the sphere.
c. both on the inside and outside surfaces of the sphere.
____ 47. The electric field outside a Van de Graaff generator may be enormous, while inside the spherical dome, the
electric field is
a. even more enormous.
b. almost as enormous.
c. zero.
____ 48. A woman's hair stands out when she is in contact with a charged Van de Graaff generator. The reason her hair
stands out is because
a. hair strands are at a high voltage.
b. she is in a strong electric field.
c. like charges repel.
d. hair is a good conductor.
____ 49. After you rub a balloon on your hair, the balloon will likely be charged
a. to less than 10 volts.
b. to several hundred volts.
c. to several thousand volts.
d. not at all.
____ 50. 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
____ 51. A beam of electrons accelerates from the back of your TV set to the screen. In order to make the beam hit the
top of the screen, charged parallel plates create a vertical electric field. How will the top plate be charged?
a. negatively
b. positively
____ 52. The electric field lines between two charges curve in space. The direction at a particular point on a curved line
is the direction of the
a. strongest field.
b. average straight line joining the charges.
c. resultant vector of the fields of the two charges at that point.
d. none of the above
____ 53. Electrical potential energy per charge is electric
a. force.
b. power.
c. potential.
d. work.
____ 54. 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.
____ 55. The electric field inside an uncharged metal ball is zero. If the ball gains a negative charge, the electric field
inside the ball will be
a. greater than zero.
b. less than zero.
c. zero.
____ 56. A 2-C charge experiences a force of 40 N when put at a certain location in space. The electric field at that
location is
a. 2 N/C.
b. 20 N/C.
c. 30 N/C.
d. 40 N/C.
e. 60 N/C.
____ 57. The electric field in a certain region of space is 30 N/C. What is the force on a 2-C charge placed in that
region?
a. 15 N
b. 2 N
c. 30 N
d. 4 N
e. 60 N
____ 58. If you use 20 J of work to push a 2-C charge into an electric field, its voltage with respect to its starting
position is
a. 10 V.
b. less than 10 V.
c. more then 10 V.
____ 59. If you use 17 J of work to push a charge into an electric field and then release the charge, as the charge flies
past its starting position, its kinetic energy is
a. more than 17 J.
b. less than 17 J.
c. 17 J.
____ 60. An electron is pushed into an electric field where it acquires a 7.0-V electric potential. If two electrons are
pushed the same distance into the same electric field, the electric potential of the two electrons is
a. 1.8 V.
b. 3.5 V.
c. 7.0 V.
d. 14.0 V.
e. 28.0 V.
____ 61. In order for there to be a flow of charge from one place to another, there must be a
a. conductor, such as a wire, connecting the two places.
b. potential difference between the two places.
c. Both A and B above
____ 62. Electrons move in an electric circuit
a. by being bumped by other electrons.
b. by interacting with an established electric field.
c. by colliding with molecules.
d. because the wires are so thin.
e. none of the above
____ 63. An ampere is a
a. unit of resistance.
b. unit of current.
c. type of charge.
d. voltage.
e. current.
____ 64. Electrical resistance in a wire depends on the wire's
a. thickness.
b. conductivity.
c. length.
d. all of the above
e. none of the above
____ 65. Compared to thin wires, electrical resistance in thick wires is
a. less.
b. the same.
c. greater.
____ 66. Electrical resistance is measured in
a. volts.
b. joules.
c. watts.
d. amperes.
e. none of the above
____ 67. A woman experiences an electric shock. The electrons making the shock come from
a. the ground.
b. the electric field in the air.
c. a nearby power supply.
d. the woman's body.
e. the object causing the shock.
____ 68. A pulsating electric field can travel through a wire at a speed of
a. less than 1 cm/s.
b. about 100 cm/s.
c. the speed of sound waves in metal.
d. nearly the speed of light.
____ 69. A wire carrying a current is normally charged
a. not at all.
b. positively.
c. negatively.
____ 70. While you are standing on the ground in your running shoes, the greatest resistance between you and the
ground is in
a. your muscles.
b. your legs.
c. the clothes you are wearing.
d. your skin.
e. the running shoes.
____ 71. The primary reason a bird can perch harmlessly on bare high voltage wires is that
a. a bird's feet are close together.
b. a bird has a very large electrical resistance.
c. there is no potential difference across the bird's feet.
d. all of the above
____ 72. Alternating current is made by
a. alternating current and voltage.
b. alternating the direction of voltage of the power source.
c. huge chemical batteries.
d. none of the above
____ 73. The frequency of AC current in North America is
a. 120 V.
b. 50 hertz.
c. 30 V.
d. 60 hertz.
____ 74. The net speed of electrons in a wire is about
a. 0.01 cm/s.
b. 10 m/s.
c. 100 kilometers per hour.
d. a few million kilometers per hour.
e. the speed of light.
____ 75. Where do the electrons come from that produce heat and light in a light bulb?
a. the power company
b. the air
c. the wall plug
d. the bulb's wire filament
e. none of the above
____ 76. When we say an appliance uses up electricity, we really are saying that
a. electrons are taken out of the circuit and put somewhere else.
b. electron kinetic energy is changed into heat and other forms of energy.
c. the main power supply voltage is lowered.
d. current disappears.
e. electric charges are dissipated.
____ 77. If you plug an electric toaster rated at 110 V into a 220-V outlet, current in the toaster will be
a. twice what it should be.
b. the same as if it were plugged into 110 V.
c. half what it should be.
d. more than twice what it should be.
e. none of the above
____ 78. Electric power is defined as
a. current times voltage.
b. current divided by voltage.
c. current times resistance.
d. resistance times voltage.
e. voltage divided by current.
____ 79. Power outlets in our homes typically have a potential difference of
a. 30 V.
b. 120 A.
c. 60 A.
d. 240 V.
e. 120 V.
____ 80. When an 8-V battery is connected to a resistor, 2 A of current flows in the resistor. What is the resistor's
value?
a. 2 ohms
b. 4 ohms
c. 8 ohms
d. 16 ohms
e. more than 16 ohms
____ 81. The current through a 5-ohm resistor connected to a 150-V power supply is
a. 1A.
b. 10 A.
c. 30 A.
d. 150 A.
e. none of the above
____ 82. A 15-ohm resistor has a 5-A current in it. What is the voltage across the resistor?
a. 5 V
b. 15 V
c. 20 V
d. 25 V
e. more than 25 V
____ 83. What is the resistance of a toaster that uses 5 A of current when connected to a 120-volt power source?
a. 5 ohms
b. 24 ohms
c. 120 ohms
d. 600 ohms
e. none of the above
____ 84. When connected to a 110-volt power supply, how much current is in a light bulb that has a resistance of 220
ohms?
a. 0.5 A
b. 2.0 A
c. 110 A
d. 220 A
e. 24,200 A
____ 85. When plugged into a 120-V wall outlet, how much current is used by an electric blanket rated at 140 W?
a. 16,800 A
b. 140 A
c. 120 A
d. 1.2 A
e. none of the above
____ 86. A 120-watt light bulb is connected to a 120-V outlet. How much current is in the light bulb?
a. 0.5 A
b. 1 A
c. 2 A
d. 6 A
e. more than 6 A
____ 87. A 60-W light bulb and a 100-W light bulb are both rated at 120 V. Which light bulb has the larger resistance?
a. the 60-W bulb
b. the 100-W bulb
c. Both have the same resistance.
____ 88. A 60-W light bulb and a 100-W light bulb are each connected to a 120-V outlet. Which light bulb has more
current in it?
a. the 60-W bulb.
b. the 100-W bulb.
c. The same amount of current flows in both.
____ 89. An electric heater is rated at 300 W for use in a 110-V circuit. The circuit breaker in the circuit can handle 12
A of current. How many heaters can be safely operated in the circuit?
a. 2
b. 3
c. 4
d. 5
e. more than 5
____ 90. A heater uses 21 A when connected to a 110-V line. If electric power costs 10 cents per kilowatt-hour in this
location, the cost of running the heater for 13 hours is _____.
a. $0.30
b. $0.75
c. $3.00
d. $7.51
e. none of the above
____ 91. A power line with a resistance of 9 ohms has a current of 80 A in it. The power dissipated in the line is
a. 360 W.
b. 720 W.
c. 1,440 W.
d. 57,600 W.
e. none of the above
Problem
92. 100,000 electrons are removed from a neutral plastic ball. What is its charge?
93. 100 electrons are added to a neutral plastic ball. What is its charge?
94. What is the magnitude of the force on an electron in an electric field of 400 N/C?
95. 48 J of work are done to push 0.1 C of charge from point A to point B in an electric field. What is the voltage
difference between points A and B?
96. How much voltage is required to make 4 amperes flow through a 12-ohm resistor?
97. A battery does 18 J of work on 10 coulombs of charge. What voltage does the battery supply?
98. What is the current in a 60-W bulb connected to a 120-V source?
99. What is the power dissipated by a toaster that has a resistance of 40 ohms and is plugged into a 120-V outlet?
100. A certain bulb with a resistance of 240 ohms is labeled 60 W. For what voltage circuit was this bulb
designed?