Knowledge of electrical charges throughout history: Origin of word electron (Greek word for amber); discovery of two types of charge: Positive and negative; like charges repel and unlike charges attract; Ben Franklin discovers conservation of charge, existence of conductors.

Charging a glass rod with silk, then inducing a polarization of charge in a conductor. Properties of conductors. Demonstration: Using balloons to demonstrate induction of positive and negative charges with conductors and non-conductors.

Friction creates a charge when combing your hair, touching a doorknob after walking on a carpet, using Saran™ Wrap and cellophane. Experiment: Beating a student with cat fur to create a charge, then discharging by touching a neon discharge tube.

Demonstration of a Van de Graaff generator used to charge confetti, causing it to jump in the air.

Force of one charge on another charge is Kqq/r^2, unit is Coulomb. A Coulomb is very large, electron has charge 1.6E-19 C. Coulomb's constant K = 9E9 N*m^2/C^2=1/(4pi*ε₀). Electrical force between two charges is analogous to force on two masses due to gravity. With 3 or more charges the force on one charge from the other two is the sum of the individual forces.

Definition of electroscope as a device for measuring charge. Demonstration of human electroscope by charging himself with the Van de Graaff and holding pieces of tinsel.

Electromagnetism through history; standard model; electric charge.

Statement; superposition for point charges and distributions; SI vs. cgs units; force from charged rod; Taylor expansions.

Work required to move charge; potential energy of configuration.

Explanation of electrical charge, with historical background; value of the elementary charge of protons and electrons; includes charge quantization and conservation.

Coulomb's Law defined, as well as ε₀. Examples of Coulomb's Law are shown with an animation of a Van de Graff generator.

Introduces the principle of superposition for electric force and works an example using three charges.

Introduction to charge and how it causes force via Coulomb's Law; description of resulting electromagnetic field.

Calculate electric field on axis of two point charges.

Calculate the strengths of the electromagnetic and gravitational forces between the electron and proton in a hydrogen atom; qualitatively compare to the forces between two planets.

Solution (PDF)

Find the mass and charge of an oil drop using electrostatics; solution explains significance of Millikan's oil-drop experiment.

Solution (PDF)

Determine the motion and vertical deflection of a charged particle in a constant electric field.

Solution (PDF)

Determine the electric force on a point charge due to two other charges.

Determine the equilibrium separation between two pendula with charged masses; use this to calculate the charge of the masses.

Identify where the electric field due to a positive and a negative point charge goes to zero.

Calculating charge necessary for two dust grains to overcome gravitational attraction.

Solution (PDF)

Finding ratio for electron and proton; distance to balance; gravity on large scales.

Solution (PDF)

Ratio of electric to gravitational forces between earth and moon for smaller electron charge; stable system.

Solution (PDF)

Finding force on central point charge before and after an outer charge is removed.

Solution (PDF)

Finding position of third charge for F = 0; potential energy of third charge and effect of perturbation.

Solution (PDF)^#

Determining experimentally whether an object carries a purported third charge.

Solution (PDF)^#

For triangular arrangement of charges, finding the E-field, the force on a charge, and the motion of a charge.

Solution (PDF)^#

Video animation showing the interaction of four equal charges: Two positive and two negative. Mention of Pauli and van der Waals forces.

Applet simulating the interaction of large numbers of positive and negative charges in a two-dimensional space.

Applet simulating the interaction of large numbers of positive and negative charges in a three-dimensional space.

Interactive applet simulating the interactions of charged particles in a two-dimensional space.

Interactive applet simulating the interactions of charged particles in a three-dimensional space.

Interactive applet simulating the behavior of two lattices of charged particles as they collide with one another.

Applet simulating the interaction between 10 positively charged particles contained in a pentagon.

Applet simulating the behavior of the charges inside the plates of a parallel plate capacitor.

Applet simulating the behavior of a conducting sphere placed between the plates of a parallel plate capacitor as it is being charged

Interactive applet simulates interaction between charged particles, with ability to view field lines and equipotential lines for the particles.

Applet in which the player tries to navigate a simple maze by changing the value of a point charge between positive and negative.