Key Terms

Key Terms

charging by induction

process by which an electrically charged object brought near a neutral object creates a charge separation in that object

conduction electron

electron that is free to move away from its atomic orbit

conductor

material that allows electrons to move separately from their atomic orbits; object with properties that allow charges to move about freely within it

continuous charge distribution

total source charge composed of so large a number of elementary charges that it must be treated as continuous, rather than discrete

coulomb

SI unit of electric charge

Coulomb force

another term for the electrostatic force

Coulomb’s law

mathematical equation calculating the electrostatic force vector between two charged particles

dipole

two equal and opposite charges that are fixed close to each other

dipole moment

property of a dipole; it characterizes the combination of distance between the opposite charges, and the magnitude of the charges

electric charge

physical property of an object that causes it to be attracted toward or repelled from another charged object; each charged object generates and is influenced by a force called an electric force

electric field

physical phenomenon created by a charge; it “transmits” a force between two charges

electric force

noncontact force observed between electrically charged objects

electron

particle surrounding the nucleus of an atom and carrying the smallest unit of negative charge

electrostatic attraction

phenomenon of two objects with opposite charges attracting each other

electrostatic force

amount and direction of attraction or repulsion between two charged bodies; the assumption is that the source charges have no acceleration

electrostatic repulsion

phenomenon of two objects with like charges repelling each other

electrostatics

study of charged objects which are not in motion

field line

smooth, usually curved line that indicates the direction of the electric field

field line density

number of field lines per square meter passing through an imaginary area; its purpose is to indicate the field strength at different points in space

induced dipole

typically an atom, or a spherically symmetric molecule; a dipole created due to opposite forces displacing the positive and negative charges

infinite plane

flat sheet in which the dimensions making up the area are much, much greater than its thickness, and also much, much greater than the distance at which the field is to be calculated; its field is constant

infinite straight wire

straight wire whose length is much, much greater than either of its other dimensions, and also much, much greater than the distance at which the field is to be calculated

insulator

material that holds electrons securely within their atomic orbits

ion

atom or molecule with more or fewer electrons than protons

law of conservation of charge

net electric charge of a closed system is constant

linear charge density

amount of charge in an element of a charge distribution that is essentially one-dimensional (the width and height are much, much smaller than its length); its units are C/m

neutron

neutral particle in the nucleus of an atom, with (nearly) the same mass as a proton

permanent dipole

typically a molecule; a dipole created by the arrangement of the charged particles from which the dipole is created

permittivity of vacuum

also called the permittivity of free space, and constant describing the strength of the electric force in a vacuum

polarization

slight shifting of positive and negative charges to opposite sides of an object

principle of superposition

useful fact that we can simply add up all of the forces due to charges acting on an object

proton

particle in the nucleus of an atom and carrying a positive charge equal in magnitude to the amount of negative charge carried by an electron

static electricity

buildup of electric charge on the surface of an object; the arrangement of the charge remains constant (“static”)

superposition

concept that states that the net electric field of multiple source charges is the vector sum of the field of each source charge calculated individually

surface charge density

amount of charge in an element of a two-dimensional charge distribution (the thickness is small); its units are $\text{C}\text{/}{\text{m}}^2$

volume charge density

amount of charge in an element of a three-dimensional charge distribution; its units are $\text{C}\text{/}{\text{m}}^3$