One major missing component from all these very well researched and intelligent answers regarding capacitors is the amp. Only use a capacitor on an un-regulated power supply amp! Stiffly regulated amps will not benefit from extra voltage, because they produce the same wattage regardless of input voltage. (see JL 5001, etc.)

 

^ interesting point... the cap is one of the items used to 'stiffen' the power supply.

Capacitance is "The standard unit of electrical capacity; the capacity of a condenser whose charge, having an electro-motive force of one volt, is equal to the amount of electricity which, with the same electromotive force, passes through one ohm in one second; the capacity, which, charged with one coulomb, gives an electro-motive force of one volt." So with a 1 farad capacitor 12 volts =>12 coulombs and 14 volts=> 14 coulombs so to build on Adams statement to drop from 14 to 12 volts the capacitor has 2 coulombs of energy to contribute on the way down to slow the slope of voltage decrease.

 

Ow, you just hurt my brain!

 

1 culomb passing by a single point, in 1 second is equal to 1 ampere