Summary
Electric charge is a quality of protons and electrons that gives them an
attractive force. Protons are positive, while electrons are negative. Neutrons
have no electrical charge.
Use Coulomb’s law to determine the magnitude of the electric
force between two charged particles with charges of q 1 and q 2 separated by a
distance of r^2.
Superposition refers to the fact that the total electric force acting on a charge
can be determined by summing up the individual contributions to the force of
each of the other charges. Electric force is a vector quantity.
The presence of a charge creates an electric field in the space that surrounds
it. The electric field vectors farther from the source charge are shorter than
those that are closer because the strength decreases as we get farther away
from the charge.
The electric field points away from positive charges and toward negative
charges.
Positive charges feel a force in the direction of the electric field and negative
charges feel a force opposite to the electric field.
Conductors are materials, such as metals, that permit the flow of charge.
Electrons are free to flow through metal and redistribute themselves.
Insulators are materials, such as wood, glass, rubber, and plastic, which
inhibit the flow of electrons. Electrons cannot travel through an insulator, so
the charge stays put in the material in which it originated.
