CHAPTER 18

Electrostatics

IN THIS CHAPTER
Summary: An electric field provides a force on a charged particle. Electric potential, also called voltage, provides energy to a charged
particle. Once you know the force or energy experienced by a charged particle, Newtonian mechanics (i.e., kinematics, conservation of
energy, etc.) can be applied to predict the particle’s motion.

Key Ideas
The electric force on a charged particle is qE , regardless of what produces the electric field. The
electric potential energy of a charged particle is qV .
Positive charges are forced in the direction of an electric field; negative charges, opposite the field.
Positive charges are forced from high to low potential; negative charges, low to high.
Point charges produce non-uniform electric fields. Parallel plates produce a uniform electric field
between them.
Electric field is a vector, and electric potential is a scalar.

Relevant Equations

Electric force on a charge in an electric field:

F = qE

Electric field produced by a point charge^1 :

Electric field produced by parallel plates: