chapter 22

Charge carriers in a metal are electrons rather than protons because electrons are a) loosely bound b) smaller c) negative d) none of the above

a) loosely bound

Rub electrons from your hair with a comb and the comb becomes a) negatively charged b) discharged c) positively charged

a) negatively charged

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) 2 V b) 0.25 V c) 4 V d) 1 V e) 0.5 V

d) 1 V

Two charges that are separated by one meter exert 1-N forces on each other. If the charges are pushed together so the separation is 25 centimeters, the force on each charge will be a) 8 N b) 4 N c) 1 N d) 16 N e) 2 N

d) 16 N

Two charged particles repel each other with a force F. If the charge of both particles is tripled and the distance between them is also tripled, then the force will be a) F/4 b) 2 F c) F/2 d) F e) none of the above

d) F

The direction of an electric field is the direction of the force exerted on a) an electron b) a molecule c) a neutral test charge d) a proton e) an atom

d) a proton

Between a pair of equal and opposite charges, field lines are a) vectors, with patterns that stem from the inverse-square law b) directed from positive to negative c) more concentrated closer to the charges d) all of the above e) none of the above

d) all of the above

Electrons can be transferred from one place to another by the process of a) induction, which means non-touching b) friction c) contact, which means touching d) all of the above e) none of the above

d) all of the above

If you rub an inflated balloon against your hair and place the balloon against the wall it will stick to the wall, illustrating a) voltage b) Coulomb's law c) conduction and insulation d) charge polarization

d) charge polarization

The primary purpose of a lightning rod is to a) attract lightning and guide it to the ground b) cancel the electric field within the structure to which it is attached c) induce a charge opposite to that of charged clouds overhead d) discharge the structure to which it is attached

d) discharge the structure to which it is attached

The fundamental force underlying all chemical reactions is a) nuclear b) gravitational c) centripetal d) electrical e) none of the above

d) electrical

To say that an object becomes electrically polarized means that a) it is only partially conducting b) its internal electric field is zero c) it is electrically charged d) its charges have been rearranged e) none of the above

d) its charges have been rearranged

To become a positive ion, an atom must a) gain a proton b) gain an electron c) lose a proton d) lose an electron

d) lose an electron

To say that electric charge is conserved means that no case has ever been found where a) quantity of negative charge on an object exactly balances positive charge b) the total quantity of charge on an object has increased c) the total charge on an object has changed d) net charge has been created or destroyed e) none of the above

d) net charge has been created or destroyed

A transistor is an example of a a) resistor b) dry cell c) transmitter d) semiconductor e) superconductor

d) semiconductor

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) half as much d) the same e) none of the above

d) the same

Insulating materials are composed of atoms with a) weak cohesive forces b) excess protons c) vastly more charge than conductors d) tightly bound outer electrons

d) tightly bound outer electrons

Superconductors are noted for their a) low cost b) high electric resistance c) bright colors d) low electric resistance e) absence of electric resistance

e) absence of electric resistance

A conductor differs from an insulator in that a conductor has more a) faster moving molecules b) protons than electrons c) energy than an insulator d) electrons than protons e) none of the above

e) none of the above

Shown are three separate pairs of point charges. Assume the pairs interact only with each other. Rank the magnitudes of the force between the pairs from largest to smallest.

A,B,C

The three pairs of metal same-size spheres have different charges on their surfaces, as indicated. Each pair is brought together, allowed to touch, and then separated. Rank from greatest to least the total amount of charge on the pairs of spheres after separation.

C,B,A

Two pellets, each with a charge of 1.5 microcoulomb (1.5×10−6 CC ), are located 3.0 cmcm (3.0×10−2 mm ) apart. Two pellets, each with a charge of 1.5 microcoulomb (1.5×10−6 CC ), are located 3.0 cmcm (3.0×10−2 mm ) apart.

F = 23 N

Two point charges are separated by 5.6 cmcm . The attractive force between them is 20 NN . Suppose that the charges attracting each other have equal magnitude. Two point charges are separated by 5.6 cmcm . The attractive force between them is 20 NN . Suppose that the charges attracting each other have equal magnitude.

QQ = 2.6×10^(−6) CC

Two charges separated by one meter exert 1-N forces on each other. If the charges are pulled 3 meters apart, the force on each charge will be a) 0.11 N b) 9 N c) 3 N d) 0 N e) 0.33 N

a) 0.11 N

Imagine a single charge q placed at one corner of a square, and that 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 (leaving the opposite corner "blank"), the electric field at the center of the square is a) F/q b) F/(2q) c) 4F/q d) F/(4q) e) none of the above

a) F/q

It is said that electric charge is conserved, which means that electric charge a) can be neither created nor destroyed b) is a whole number multiple of the charge of one electron c) is sometimes negative d) will interact with neighboring electric charges e) may occur in an infinite variety of quantities

a) can be neither created nor destroyed

Electric potential, measured in volts, is the ratio of electric energy to the amount of electric a) charge b) current c) voltage d) resistance e) none of the above

a) charge

The electrical force between charges is strongest when the charges are a) close together b) far apart c) either of these d) need more information

a) close together

The force that binds atoms together to form molecules is a) electrical b) gravitational c) nuclear d) centripetal e) none of the above

a) electrical

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) both electrons and neutrons d) none of the above

a) electrons that surround the nucleus

An electrically charged atom is an a) ion b) isotope c) both of these d) neither of these

a) ion

It is said that electric charge is quantized, which means that the charge on an object a) is a whole-number multiple of the charge of one electron b) is sometimes positive c) can be neither created nor destroyed d) may occur in an infinite variety of quantities e) will interact with neighboring electric charges

a) is a whole-number multiple of the charge of one electron

Two charged particles held a certain distance apart are released. As they move, the force on each particle increases. Therefore, their charges have a) opposite signs b) the same sign c) the same mass d) the same size e) need more information

a) opposite signs

A negatively-charged rod is held near an aluminum can that rests on a dry wood table. If you momentarily touch the opposite side of the can with your finger, the can becomes a) positively charged b) completely discharged c) negatively charged d) partially discharged e) none of the above

a) positively charged

Although the energy per coulomb of a high-voltage party balloon is high, the energy transfer that occurs if you touch it is low due to a) the relatively small amount of charge b) the small electric potential c) rubber being a poor conductor d) all of the above

a) the relatively small amount of charge

The vast numbers of electrons in a coin don't fly off the surface because a) they are attracted by an equal number of protons b) mutual repulsion is incomplete c) they are strongly bonded to their atoms d) all of the above e) none of the above

a) they are attracted by an equal number of protons

During a lightning strike you don't want to be inside a building framed with a) wood b) iron c) steel d) aluminum

a) wood

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) zero b) greater than zero c) less than zero

a) zero

When a car is struck by lightning, the resulting electric field inside the car is a) zero b) small enough to be safe for a passenger inside c) normally huge, but for a brief time

a) zero

Assume that 10 J of work pushes a charge initially at rest into an electric field. If the charge is then released, it flies back to its starting position with a kinetic energy of a) 5 J b) 10 J c) zero d) more than 10 J e) need more information

b) 10 J

The electrical force on a 2-C charge is 60 N. The electric field where the charge is located is a) 120 N/C b) 30 N/C c) 20 N/C d) 60 N/C e) 240 N/C

b) 30 N/C

Two charges that are 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) 8 N b) 4 N c) 1 N d) 2 N e) none of the above

b) 4 N

The pair of protons in the nucleus of a helium atom a) repel orbiting electrons b) attract a pair of orbiting electrons c) both of these d) neither of these

b) attract a pair of orbiting electrons

An electron and a proton a) repel each other b) attract each other c) neither attract nor repel each other

b) attract each other

An electroscope is charged positively as indicated by foil leaves that stand apart. As a negative charge is brought close to the electroscope, the leaves become a) farther apart b) closer together c) motionless

b) closer together

Two protons attract each other gravitationally and repel each other electrically. The stronger of these two forces is a) gravitation b) electrical c) neither of these

b) electrical

A proton and an electron are placed in an electric field. Which undergoes the greater acceleration? a) proton b) electron c) both accelerate equally d) none of the above

b) electron

To become a negative ion, an atom must a) lose an electron b) gain an electron c) lose a proton d) gain a proton

b) gain an electron

Conducting materials are composed of atoms with a) strong cohesive forces between them b) loose outer electrons c) excess neutrons compared with protons d) vastly more charge than insulators

b) loose outer electrons

Superconductors most often require a) high operating temperatures b) low operating temperatures c) magnets

b) low operating temperatures

Which of these has the greatest mass? a) electron b) proton c) both of these d) neither of these

b) proton

When the distance between two charges is halved, the electrical force between them a) halves b) quadruples c) is reduced by 1/4 d) doubles e) none of the above

b) quadruples

Two charged particles held a certain distance apart are released. As they move, the acceleration of each decreases. Therefore, their charges have a) opposite signs b) the same sign c) need more information

b) the same sign

The electric field between oppositely-charged parallel plates is a) composed of field lines in opposite directions b) uniform c) stronger at the ends d) none of the above

b) uniform

If 10 J of work is used in pushing 1 C of charge into an electric field, its electric potential relative to its starting position is a) more then 10 V b) less than 10 V c) 10 V d) none of the above

c) 10 V

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) 2 F b) F/2 c) F d) F/4 e) none of the above

c) F

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) 2 F b) F c) F/2 d) F/4 e) none of the above

c) F/2

A fundamental rule of electricity is that a) unlike kinds of charges attract b) like kinds of charges repel c) both of these d) neither of these

c) both of these

A semiconductor can be a) a conductor b) an insulator c) both of these d) neither of these

c) both of these

Every isolated proton in the universe is surrounded by its own a) gravitational field b) electric field c) both of these d) neither of these

c) both of these

Normally a small party balloon charged to several thousand volts will have a relatively small amount of a) charge b) energy c) both of these d) neither of these

c) both of these

The electrical force between electric charges depends only on their a) magnitude b) separation distance c) both of these d) neither of these

c) both of these

Electrostatics is a branch of electricity that focuses on a) electrical charge b) electrical force c) both of these when static d) none of the above

c) both of these when static

Two charged particles held close to each other are released. As they move, their speeds increase. Therefore, their charges have a) the same sign b) opposite signs c) either of these d) need more information

c) either of these

Just as "gravity" is the study of a wide range of gravitational interactions, "electricity" is the study of a wide range of a) electrical charges b) electrical forces c) electrical interactions d) none of the above

c) electrical interactions

A positive charge and a negative charge held a certain distance apart are released. As they move, the force on each particle a) decreases b) stays the same c) increases

c) increases

A positively-charged rod is held near an aluminum can that rests on a dry wood table. If you momentarily touch the opposite side of the can with your finger, the can becomes a) completely discharged b) partially discharged c) negatively charged d) positively charged e) none of the above

c) negatively charged

If you comb your hair and the comb becomes positively charged, then your hair becomes a) positively charged b) uncharged c) negatively charged

c) negatively charged

Which of these does NOT have an electrical charge? a) electron b) proton c) neutron d) all of the above e) none of the above

c) neutron

If electrons are stripped from an atom it becomes a a) different element b) molecule c) positive ion d) negative ion

c) positive ion

Imagine a single charge q placed on one corner of a square, and that the electric field at the center of the square is F/q. If additional equal charges are placed on the other three corners, the electric field at the center of the square due to these four equal charges is a) F/(2q) b) 4F/q c) F/(4q) d) F/q e) none of the above

e) none of the above

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) four times as much b) half as much c) the same d) twice as much e) none of the above

e) none of the above

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 halved, then the force will be a) F/4 b) F c) 2 F d) F/2 e) none of the above

e) none of the above

A positive ion has more a) protons than neutrons b) electrons than neutrons c) electrons than protons d) neutrons than protons e) protons than electrons

e) protons than electrons

A main difference between gravitational and electric forces is that electrical forces a) obey the inverse-square law b) act over shorter distances c) attract d) are weaker e) repel or attract

e) repel or attract

The unit of electric charge, the coulomb, is the charge on a a) specific number of neutrons b) single electron c) quark d) neutron e) specific large number of electrons

e) specific large number of electrons

Two pellets, each with a charge of 1.5 microcoulomb (1.5×10−6 CC ), are located 3.0 cmcm (3.0×10−2 mm ) apart. What would be the mass of an object that would experience this same force in Earth's gravitational field? Express your answer to two significant figures and include the appropriate units.

mm = 2.3 kg

Find the voltage change when an electric field does 9.0 JJ of work on a 0.00010-CC charge. Express your answer to two significant figures and include the appropriate units.

ΔV = 90 kV

Find the voltage change when the same electric field does 18 JJ of work on a 0.00020-CC charge. Express your answer to two significant figures and include the appropriate units.

ΔV = 90 kV