Chapter 22: Electrostatics

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

10J

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

10V

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

1V

The electrical force on a 2-C charge is 60 N. The electric field where the charge is located is

30N/C

A semiconductor can be

A conductor and an insulator

The direction of an electric field is the direction of the force exerted on

A proton

An electric field is basically _________.

A vector quantity

A common naturally-polarized bit of matter is

A water molecule

How does the charge of one electron compare to that of another electron? How does it compare with the charge of a proton? How do the masses of protons and electrons compare?

All electrons have the same charge. Electron charge is equal and opposite to the proton charge. A proton has 1800 times the mass of an electron.

The operation of a microwave oven makes use of

An oscillating electric field, flip flopping of polarized molecules, and the polar nature of water molecules

A reason for electric shielding inside a conductor is that any free electrons inside would

Be set in motion until equilibrium is established on the outside

An uncharged pith ball is suspended by a nylon fiber. When a negatively-charged rubber rod is brought near the pith ball, without touching, the ball

Becomes polarized

Electric shielding within a conductor is a consequence of

Both the attraction and repelling nature of electricity, the balancing of opposing forces, and cancellation of electric field lines

If you rub an inflated balloon against your hair and place the balloon against the wall it will stick to the wall, illustrating

Charge polarization

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

Closer together

A highly-charged party balloon is not dangerous when it _________.

Contains little overlap energy

Between a pair of equal and opposite charges, field lines are

Directed orm positive to negative, vectors with patterns that stem from the inverse- square law, more concentrate closer to the charges

Every isolated proton in the universe is surrounded by its own

Electric field and gravitational field

Normally a small party balloon charged to several thousand volts will have a relatively small amount of

Energy and charge

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

F/2

Electrons can be transferred from one place to another by the process of

Friction, induction which means non-touching, contact which means touching

To say that an object becomes electrically polarized means that

Its charged have been rearranged

Charge carriers in a metal are electrons rather than protons because electrons are

Loosely bound

An uncharged pith ball is suspended by a nylon fiber. When a positively-charged rubber rod is brought near, the pith ball

Moves toward the rod

Much of the charge on a conducting cube is

Mutually repelled toward its corners

If you comb your hair and the comb becomes positively charged, then your hair becomes

Negatively charged

Coulomb's law is most similar to which of these laws?

Newton's law of gravity

Two charged particles held a certain distance apart are released. As they move, the force on each particle increases. Therefore, their charges have

Opposite signs

A balloon will stick to a wooden wall if the balloon is charge

Positively or negatively

The electrical force between electric charges depends only on their

Separation distance and magnitude

Two charged particles held a certain distance apart are released. As they move, the acceleration of each decreases. Therefore, their charges have

The same sign

Insulating materials are composed of atoms with

Tightly bound outer electrons

Electric charge distributes itself on conducting surfaces

With greater concentration on more curved parts and such that the electric field inside is zero

When a car is struck by lightning, the resulting electric field inside the car is

Zero

Superconductors are noted for their

absence of electric resistance.

The pair of protons in the nucleus of a helium atom

attract a pair of orbiting electrons

An electron and a proton

attract each other.

Electrostatics is a branch of electricity that focuses on

both of these when static. electrical force. electrical charge

Electric charge can be transferred from one conducting body to another _________.

by both contact and closeness

It is said that electric charge is conserved, which means that electric charge

can be neither created nor destroyed.

Electric potential, measured in volts, is the ratio of electric energy to the amount of electric

charge

The electrical force between charges is strongest when the charges areclose together

close together

Just as "gravity" is the study of a wide range of gravitational interactions, "electricity" is the study of a wide range of

electrical interactions.

The force that binds atoms together to form molecules is

electrical.

The fundamental force underlying all chemical reactions is

electrical.

Two protons attract each other gravitationally and repel each other electrically. The stronger of these two forces is

electrical.

A proton and an electron are placed in an electric field. Which undergoes the greater acceleration?

electron

In an electrically neutral atom the number of protons in the nucleus is equal to the number of

electrons that surround the nucleus.

Lillian safely touches a 100,000-volt Van de Graaff generator. Although the voltage is high, the relatively small amount of charge means a relatively small amount of

energy transfer.

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

f/q

To become a negative ion, an atom must

gain an electron

A positive charge and a negative charge held a certain distance apart are released. As they move, the force on each particle

increases

An electrically charged atom is an

ion.

A fundamental rule of electricity is that

like kinds of charges repel.and unlike kinds of charges attract.

Rub electrons from your hair with a comb and the comb becomes

negatively charged.

To say that electric charge is conserved means that no case has ever been found where

net charge has been created or destroyed.

Which of these does NOT have an electrical charge?

neutron

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

none

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

none

The electric field inside the dome of a Van de Graaff generator depends on the

none

The net charge on a charged capacitor depends on

none

Before a thunderstorm, clouds in the sky likely become

polarized

If electrons are stripped from an atom it becomes a

positive ion

Which of these has the greatest mass?

proton

A positive ion has more

protons than electrons.

A main difference between gravitational and electric forces is that electrical forces

repel or attract.

A transistor is an example of a

semiconductor 3

The unit of electric charge, the coulomb, is the charge on a

specific large number of electrons.

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

the relatively small amount of charge.

When we say charge is conserved, we mainly mean that charge can be _________.

transferred without loss like money in a bank

The electric field between oppositely-charged parallel plates is

uniform

Electric potential, unlike electric potential energy, is measured in units of _________.

volts

During a lightning strike you don't want to be inside a building framed with

wood

Most atoms normally have a net charge that is _________.

zero

The electric field inside an uncharged metal ball is zero. If the ball is negatively charged, the electric field inside the ball is then

zero

The electric field inside the dome of a highly-charged Van de Graaff generator is _________.

zero

The net charge on a polarized molecule is normally _________.

zero

The net charge on an energized capacitor is normally _________.

zero