ELECTROSTATICS

The interactions and properties of configurations of charge.

Students should be able to:

Static Electricity
• explain the difference between an insulator and a conductor.
• using the concept of polarization, explain why a charged object will attract to a neutral one.
• use Coulomb's law and superposition to calculate the force between multiple charges.
• explain why the leaves on an electroscope separate.
• explain how to charge an object using either friction, conduction, or induction.
• given a description of events, predict whether two objects with attract or repel (think tape, or balloons on walls.)

The Electric field Model and the Various Potentials
• use superposition to calculate the elctric field and potential of configurations involving many charges.
• describe the interactions in a system of charges using each of the 4 standard descriptions: forces, electric fields, potential energy, or electric potential.
• given one of the above, determine the charge configuration responsible for it.
• translate between electric field, electric potentials, forces, and potential energy descriptions of systems.
• state the difference between potential energy, electric potential, force, and electric field.
• plot the electric field, potential, or potential energy as a function of distance for various charge configurations.
• draw force and electric field vectors with appropriate lengths.


• given a charge configuration, draw equipotential lines at equal volatage intervals.
• given the potential of a system, find the electric field.
• use the symmetries of a charge confuguration to guess what the electric field might look like.


• determine the accleration of a charged object in an electric field.
• use the force on charges in electric fields to describe why charges arrangethemselves such that the electric field in a conductor is zero.
• predict the motion of a charge in an electric field.
• determine the kinetic energy of a particle a various points in a potential.
• determine the of a charged particle in a potential.

Electric Dipoles
• explain what the polarization vector of a dipole is and how to increase and decrease the strength of a dipole.
• describe how a dipole will move (both rotations and translations) in both uniform and non-uniform electric field (i.e. next to a point charge).
• calculate the force between a permenant dipole and an ion, two permenant dipoles, or a permenant dipole and an indiced dipole.
• explain how a dipole can be induced in an electric field.

Gauss's law
• given a charge distrubution, determine the flux through an arbitrary closed surface.
• calculate the flux through a surface.
• state Gauss's law in words and justify its meaning using the water analogy.
• use Gauss's law to determine the electric field made by complex (though symmetric) charge configurations.
• use Gauss's law to explain why all the charge inside a conductor rests on the surface.
• explain why only charges inside a closed surface contribute to the flux through close surface.
• explain how Gauss's law contains all of electrostatics, and thus makes it into the pantheon of Maxwell's Equations.