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# 2: Electrostatic Energy

• 2.1: Potential Energy of Charge Assembly
Charges interact through electric forces, which do work when the charges are moved. Assembling collections of charge therefore results in a potential energy change.
• 2.2: Electrostatic Potential
We defined an electric vector field as the force on a charge divided by that charge, so that it depends only on the source charges. We now do the same to define a scalar potential field by dividing the potential energy of a charge by that charge.
• 2.3: Computing Potential Fields for Known Charge Distributions
Just as we did for electric fields, we can calculate the potential field of a given charge distribution. While the procedures of these two calculations are similar, there are some important differences.
• 2.4: Capacitance
Electrical potential energy is typically stored by separating oppositely-charged particles and storing them on different conductors. Such systems of energy-storing, oppositely-charged conductors are called capacitors.
• 2.5: Dielectrics
We defined a perfect insulator as a substance that doesn't allow for any movement of electric charge. But in fact while insulators don't allow charge to migrate freely, they do allow charges to displace slightly, and this affects the electric field within the substance.
• 2.6: Static Networks
We move now into more practical considerations for capacitors, namely what happens when we actually connect them to each other and to batteries with conductors.