University Physics Volume 2

# 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 a 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 $C/m2C/m2$
volume charge density
amount of charge in an element of a three-dimensional charge distribution; its units are $C/m3C/m3$