The space between the plates of a charged capacitor is filled by an electric field where energy is stored. The stored energy in a capacitor is calculated by the next formulas.
Formula 1
W = ½ x C x V2
Where:
W is the stored energy in joules (J)
C is the capacitance in farads (F)
V is the voltage between the capacitor´s plates in volts (V)
Formula 2
W = ½ x Q X V
Where:
W is the stored energy in joules (J)
Q is the charge in coulombs (C)
V is the voltage between plates in volts (V)
Application Example:
In a xenon flasher a 200 µF capacitor is charged with 300 V from a DC converter. How much energy can delivered by the xenon lamp in one flash considering the total discharge when releasing the stored energy?
Data:
C = 300 µF = 300 x 10-6 F
V = 300 V
Applying formula 1:
W = 0,5 x 300 x 10-6 x 300 x 300
W = 45 000 x 10-6
W = 45 x 10-3
W = 45 mJ
