Energy storage in
capacitors
A capacitor is capable of
storing internal energy, due to charge begin moved across the voltage
difference. For moving a small charge Dq across a capacitor, the change in potential energy is:
,
where q is the charge already on the
capacitor. As a capacitor is charged fro q=0, the first charges comes
on to the capacitor while the capacitor has little charge, and hence do little
to the internal energy. While the last charges surmount the entire voltage
difference. With a little calculus one can show:
Both forms for the energy, U, will be useful.
