Capacitor Energy Calculator
Calculate energy storage, power delivery, and energy density for capacitors
Capacitor Energy Parameters
Calculation Results
Energy Formulas:
E = ½CV² (using capacitance and voltage)
E = ½QV (using charge and voltage)
E = ½Q²/C (using charge and capacitance)
Example Calculations
Example 1: Camera Flash Capacitor
Given: C = 300 µF, V = 20 V
Find: Energy stored
Solution: E = ½CV² = ½ × 300×10⁻⁶ × 20² = 0.06 J = 60 mJ
Charge: Q = CV = 300×10⁻⁶ × 20 = 6 mC
Example 2: Small Signal Capacitor
Given: C = 120 pF, V = 1.5 V
Find: Energy stored
Solution: E = ½CV² = ½ × 120×10⁻¹² × 1.5² = 1.35×10⁻¹⁰ J = 0.135 nJ
Application: Low-power electronics, timing circuits
Example 3: Power Supply Filter
Given: C = 1000 µF, V = 12 V
Find: Energy and charge
Energy: E = ½CV² = ½ × 1×10⁻³ × 12² = 0.072 J = 72 mJ
Charge: Q = CV = 1×10⁻³ × 12 = 12 mC
Energy Formulas
Primary Formula
E = ½CV²
Most common form
Using Charge
E = ½QV
When charge is known
Charge-Capacitance
E = ½Q²/C
Alternative form
Energy Density
u = ½ε₀εᵣE²
Per unit volume
Energy Units
Common Reference:
1 kWh = 3.6 MJ
Energy Applications
pJ - nJ Range
µJ - mJ Range
J - kJ Range
Safety Notes
Understanding Capacitor Energy Storage
How Capacitors Store Energy
Capacitors store energy in the form of electrostatic potential energy within the electric field between their plates. When a voltage is applied, charges accumulate on the plates, creating an electric field that contains the stored energy.
Why ½ in the Formula?
The factor of ½ in the energy formula E = ½CV² comes from the fact that the voltage across a capacitor builds up gradually during charging. The average voltage during charging is V/2, hence the energy is ½QV rather than QV.
Energy vs. Power
Energy (measured in joules) is the total amount stored, while power (measured in watts) is the rate of energy delivery. Capacitors can deliver their stored energy very quickly, making them useful for high-power applications like camera flashes.
Practical Applications
Energy Storage
Supercapacitors can store significant energy for applications like regenerative braking, backup power, and peak power assistance.
Power Delivery
Fast discharge capability makes capacitors ideal for camera flashes, defibrillators, and pulsed laser systems.
Filtering
Energy storage helps smooth voltage fluctuations in power supplies and audio circuits.
Energy Storage Comparison
| Storage Type | Energy Density | Power Density | Typical Applications |
|---|---|---|---|
| Ceramic Capacitors | Low | Very High | Decoupling, filtering |
| Electrolytic Capacitors | Medium | High | Power supplies, audio |
| Supercapacitors | High | Very High | Energy storage, backup power |
| Lithium Batteries | Very High | Medium | Portable devices, EVs |