Chapter 22 Physics: Electrostatics

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

-induction, which means non-touching. -contact, which means touching. -friction.

Electric charge distributes itself on conducting surfaces

-with greater concentration on more curved parts. -such that the electric field inside is zero.

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

0.11 N

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

1 V

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

10 J

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

10 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

16 N

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

30 N/C

Electricity

A General term for electrical Phenomena, much like gravity has to do with gravitational phenomena.

Insulator

A material that does not contain free charged particles & through which charge does not easily flow.

Superconductor

A material that is a perfect conductor with zero resistance to the flow of electric charge.

Semiconductor

A material with properties that fall between those of a conductor and an insulator & whose resistance can be affected by adding impurities.

Capacitator

An electrical device- (in simplest form) A pair of parallel conducting plates separated by a small distance- that stores electric charge and energy

Conductor

Any material that has free charged particles that easily flow through it when an electrical force acts on them.

Conservation of Charge

Electric charge is neither created nor destroyed. Total charge before interaction = total charge after

Electric Field

Electrical force per unit of charge. *The field can be considered an "aura" surrounding charged objects and is a storehouse of electric energy. *About a charged point, the field decreases with distance according to the inverse-square law, like a gravitational field. -Between oppositely charged parallel plates, the electric field is uniform: *Electric Field = F/q*

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

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

F/2

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

Given that k=9.0×109N⋅m2/C2 (the proportionality constant for Coulomb's law), select the correct equations that show that the force between the charges is 1×109N.

F=kq1q2r2=(9.0×109N⋅m2/C2)⋅(0.3C)⋅(0.3C)(0.9m)2=1×109N

The part of an atom with the greatest mass is

Proton

Coulomb

The SI unit of electric charge. *One Coulomb (C) is equal to the total charge of 6.25 X 10^18 electrons*

Electric Potential

The electric potential energy per unit of charge, measured in volts, often called Voltage. *Voltage = Electric potential energy / Charge*

Electric Potential Energy

The energy a charged object possesses by virtue of its location in an electric field.

Charging by Induction

The redistribution of electric charges in and on objects caused by the electrical influence of a charged object close by but not in contact (not touching)

Coulomb's Law

The relationship among electric force, charge, and distance. *F = k ((q1 x q2) / d2))* -charges with alike signs have a repulsive force -charges with unlike signs have an attractive force

Electrostatics

The study of electric charge at rest (not in motion, as in electric currents)

Electrically Polarized

The term applied to an atom or molecule in which the charges are aligned so that one side has a slight excess of positive charge and the other side has a slight excess of negative charge.

Charging by Contact

The transfer of electric charges between objects by rubbing or touching. (touching)

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

a proton

A common naturally-polarized bit of matter is

a water molecule

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.

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

A semiconductor can be

both a conductor and an insulator

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

charge

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

charge & energy

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

The fundamental force underlying all chemical reactions is

electrical

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

electron

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

The operation of a microwave oven makes use of

flip flopping of polarized molecules. the polar nature of water molecules. an oscillating electric field.

It is said that electric charge is quantized, which means that the charge on an object

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

Rules of Electricity

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

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

loosely bound

become a positive ion, an atom must

lose an electron.

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

moves toward the rod

Much of the charge on a conducting cube is

mutually repelled toward its corners.

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

negatively charged

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.

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

positively or negatively

When the distance between two charges is halved, the electrical force between them

quadruples

Two charged particles held close to each other are released. As they move, their speeds increase. Therefore, their charges have

the same or opposite signs

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

Particle A has twice the charge of nearby particle B. Compared to the force on Particle A, the force on Particle B is

the same.

Insulating materials are composed of atoms with

tightly bound outer electrons.

The electric field between oppositely-charged parallel plates is

uniform

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