Chapter 12 | Electrostatic Phenomena

Voltage

A change or difference in electric potential measured in volts

Coulomb's law

A description of how electrostatic force varies with quantity of charge and distance: electrostatic force is proportional to the size of each of the charges and inversely proportional to the square of the distance between two charges

Capacitor

A device for storing electric charge

Insulator

A material that does not ordinarily permit a flow of charge through it (ex: glass, plastic, ceramics, paper, and oil)

Conductor

A material that readily allows charge to flow (ex: copper, silver, iron, gold, salt solution, and acids)

Semiconductor

A substance with properties intermediate between those of electrical insulators and conductors. A fast growing use of semi conductors is computer chips, where their properties can be customized (ex: silicon, and germanium)

Electric dipole

Consists of two equal magnitude electric charges opposite in sign separated by a small distance.

Electron

Extremely small, negatively charged particles present in all atoms

Field lines

Graphic illustrations of electric and magnetic fields

A pair of charged particles with the same polarity ______, and a pair of charged particles with opposite polarities _____

Repel, attract

Triboelectric charging

Rubbing transfers charge from one body to another

Induction

The ability of an object to produce electric charge or magnetism in another by the action of its field rather than by touching

Electric charge

The electromagnetic property of an object that produces electrostatic force. A transfer of electrons to or from an object makes it electrically positive or negative

Electrostatic force

The force exerted by one stationary charge on another independently of their motion. The electrostatic force holds atoms together and binds one atoms together and binds one atom to another in liquids and solids

Electric potential

The potential energy per amount of positive electric charge

Ionize

To add or remove electrons form an atom or molecule

Polarize

To separate positive and negative areas of charge on an object, for example, a magnetic or electrically charge body.

(T/F) Charge can move on conductors

True

(T/F) Electric force is a vector; has magnitude AND direction

True

There are three charges of equal magnitude located on the corners of a square. Two are negative, and one is positive, as indicated on the diagram.At the center of the square, the electric field would be; (.)-----(-) A B x C D (-)-----(+) a. A directed upward to the left b. B directed upward to the right c. C directed downward to the right d. D directed downward to the left e. zero

a. A directed upward to the left

There is a uniform electric field that points to the South. Which statement(s) are correct? (select all that apply) a. A negative charge will experience a force to the North. b. A positive charge potential energy will increase if it moves North. c. A positive charge will experience a force to the North. d. A negative charge potential energy will increase it if it is moved North.

a. A negative charge will experience a force to the North. b. A positive charge potential energy will increase if it moves North.

A proton and an electron that are placed near one another, with no other objects nearby, will: a. accelerate toward each other. b. accelerate away from each other. c. remain motionless. d. move away from each other at constant speed.be pulled together at constant speed.

a. accelerate toward each other.

Suppose you are holding a negative charge q, and you are able to walk while carrying that charge. Suppose also that there is a positive charge Q that is stationary. The potential energy of charge q will increase if you walk: a. farther from the positive point charge Q b. nearer the positive point charge Q

a. farther from the positive point charge Q

There is one, and only one, point charge; it has a negative value -q. The letters A, B and C designate three points in space.(a - c) The directions of the electric field at these points are: c---q(-)---a---------b what is the direction of each point?

a: to the left b: o the left c: to the right

There is one, and only one, point charge; it has a positive value q. The letters A, B and C designate three points in space.(a - c) The directions of the electric field at these points are: c---------a---+q+---b what is the direction of each point?

a: to the left b: to the right c: to the left

There are two, and only two, point charges; they have a positive value q and a negative value -q, as shown in the diagram. The letters A, B, C, and D designate four points in space. The directions of the electric field at these points are: c---q(-)---a---q(+)---b d what is the direction of each point?

a: to the left b: to the right c: to the right d: to the left

Suppose you are holding a positive charge q, and you are able to walk while carrying that charge. Suppose also that there is a positive charge Q that is stationary. The potential energy of charge q will decrease as you walk: a. nearer the positive point charge Q b. father from the positive point charge Q

b. father from the positive point charge Q

Consider three objects: a nylon rod, a metal sphere, and a metal bar. Initially they are all far away from one another. The nylon rod is charged negatively by rubbing it. You next bring the negatively charged nylon rod near one side of a metal sphere, and then while holding the nylon rod in position near the metal sphere, you touch the metal bar to the opposite side of the metal sphere. What is the sign of the charge acquired by the metal bar? a. neutral b. positive c. negative

c. negative

The electric field that is produced by a moving negative charge: a. points away from the charge; its velocity is not a factor b. points in the same direction as the charge's velocity c. points toward the charge; its velocity is not a factor d. points in the direction opposite to the charge's velocity

c. points toward the charge; its velocity is not a factor

Suppose that you have two charged objects separated by a certain distance. Then you double the distance. Will the electrostatic force that one object exerts on the other be reduced to one-half its original value? a. Yes, since the Coulomb force varies inversely as the distance between the charges, doubling the distance reduces the force by a factor of one-half. b. Yes, since the Coulomb force varies exponentially between the charges, doubling the distance increases the force by a factor of 2. c. No, since the Coulomb force varies as the square of the distance between the charges, doubling the distance increases the force by a factor of 4. d. No, since the Coulomb force varies inversely as the square of the distance between the charges, doubling the distance reduces the force by a factor of one-fourth.

d. No, since the Coulomb force varies inversely as the square of the distance between the charges, doubling the distance reduces the force by a factor of one-fourth.

Suppose that you have two charges that are separated by a certain distance. Without changing the distance, both charges are both doubled in magnitude. Will the force that one charge exerts on the other also be doubled? a. Yes, the force between the two charges will be doubled since the Coulomb force between the charges varies as the magnitude of the two charges, so that doubling each gives a two-fold increase. b. No, the force between the two charges will be halved since the Coulomb force between the charges varies inversely as the magnitude of the two charges, so that doubling each gives a two-fold decrease. c. No, the force between the two charges will be one-fourth the original since the Coulomb force between the charges varies inversely as the product of the two charges, so that doubling each gives a four-fold decrease. d. No, the force between the two charges will be quadrupled since the Coulomb force between the charges varies as the product of the two charges, so that doubling each gives a four-fold increase.

d. No, the force between the two charges will be quadrupled since the Coulomb force between the charges varies as the product of the two charges, so that doubling each gives a four-fold increase.

Suppose there is a negative charge, and it moves in the same direction as the electric field. Does the potential energy of the negative charge increase or decrease? a. The potential energy of the negative charge increases because the force on the charge will be the same direction as the field. b. The potential energy of the negative charge decreases because the force on the charge will be the same direction as the field. c. The potential energy of the negative charge decreases because the force on the charge will be opposite the direction to the field. d. The potential energy of the negative charge increases because the force on the charge will be opposite the direction to the field.

d. The potential energy of the negative charge increases because the force on the charge will be opposite the direction to the field.

There is one, and only one, point charge; it has a positive value q. The letters A, B and C designate three points in space.(a - c) The directions of the electric field at these points are: c---------a---q(+)---b The magnitude of the electric field is: a. the same smaller value at A and B, and a larger value at C b. the same smaller value at A and C, and a larger value at B c. the same larger value at A and C, and a smaller value at B d. the same larger value at A and B, and a smaller value at C

d. the same larger value at A and B, and a smaller value at C

There is one, and only one, point charge; it has a negative value -q. The letters A, B and C designate three points in space.(a - c) The directions of the electric field at these points are: c---q(-)---a---------b The magnitude of the electric field is: a. the same smaller value at A and B, and a larger value at C b. the same larger value at A and B, and a smaller value at C c. the same smaller value at A and C, and a larger value at B d. the same larger value at A and C, and a smaller value at B

d. the same larger value at A and C, and a smaller value at B

There are four charges of equal magnitude located on the corners of a square. Two are negative, and two are positive, as indicated on the diagram. At the center (x) of the square, the electric field would be: (+)-----(-) A B x C D (-)-----(+) a. A directed upward to the left b. B directed upward to the right c. C directed downward to the right d. D directed downward to the left e. zero

e. zero

Electric field

the electric force per unit of positive charge exerted on an object if it were placed at that point. It is a property of space surrounding a distribution of electric charges.