Energy in Capacitors

The area under the line

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Stored energy $E = \tfrac12 CV^2$: the area under the voltage–charge line.
• Charging from a battery wastes half the energy as heat.
• Capacitors hold far less energy than batteries but deliver it fast.

Steps

1. Charging costs more and more
2. Store half a joule
3. Where did it go?
4. Capacitor or battery?
5. A supercapacitor
6. Sharing charge