1. Capacitance
Revised: 2012Aug06

2. 3. Capacitance 2
Leyden Jars
Volta’s law of capacitance
Energy storage

3. a. Leyden Jar 3
Invented in 1745 by Pieter van Musschenbroek (1700–1748) as a device to store “electric fluid” in a bottle

4. b. Alessandro Volta’s law of Capacitance4
1776 Law of Capacitance: Stored charge is proportional to applied voltage: Q=VC
Capacitance “C” is measure of ability to store charge.
Units: Farad=Coul/Volt
Common unit is “microfarad”

5. bii. Parallel Plate Capacitor5
Capacitance is a function of geometry of plates:

6. biii. Capacitors in circuits6
Capacitors in Parallel is like 2 tanks next to each other (same voltage). Total capacitance: C = C1+C2
Capacitors in series (have same charge), total capacitance is:

7. c. Capacitive Energy Recall spring: F=kx, energy stored:7
Recall spring: F=kx, energy stored:
For capacitor: Q=CV, energy stored
Energy is stored in the electric field between the plates

8. References 8 Misc http://www.circuitstoday.com/working-of-a-capacitor
static electricity animations at
History at: