Electricity and Magnetism

Chapter 14

Energetics of Capacitance

Recently, we loosely argued that upon connecting an uncharged capacitor to something that

had a voltage difference, some charge would flow to the plates. Any question of energetics

was cursorily dismissed by saying,

“Within a conductor in electrostatic equilibrium, charge can move around without

requiring net energy input (or dissipation), because the entire conductor is at

constant electric potential, and besides, the electric field vanishes, too.”

At the time, we merely needed to establish the plausibility of charge migration and the

system’s evolution toward electrostatic equilibrium.

[These arguments break dow n