Physics 7D Chapter 21

something has become charged

acquired a net electric charge

electrostatics

interactions between electric charges that are at rest

electron

negatively charged

neutron

uncharged

proton

positively charged

nucleus

small, dense core of an atom made of protons and neutrons

atomic number

number of protons or electrons in a neutral atom of an element

positive ion

when one or more electrons are removed from an atom

negative ion

an atom that has gained one or more electrons

ionization

the gain or loss of electrons

principle of conservation of charge

the algebraic sum of all the electric charges in any closed system is constant

conductors

permit easy movement of charge through them; most metals

insulators

do not permit easy movement of charge through them; most nonmetals

charging by induction

when object 1 gives object 2 the opposite charge without losing any of its original charge

point charges

charged objects that are very small in comparison to the distance (r) between them

Coulomb’s law

principle of superposition of forces

when two charges exert forces simultaneously on a third charge, the total force acting on that charge is equal to the vector sum of the forces that the two charges would exert individually

electric field

electric force per unit charge

test charge

a small charged object

source point

location of charge

field point

point (P) where we are determining the field

vector field

infinite set of vector quantities

electrostatic force

electric field at every point within material of conductor must be zero

electric dipole

pair of point charges with equal magnitude and opposite sign