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Capacitor Calculator (Energy & RC Time Constant)
Computes capacitive charge, stored electrostatic energy, and RC circuit time constants (τ = R·C).
Capacitor Stored Energy & RC Transient Curve
Computes electrostatic charge ($Q = CV$), stored energy ($E = \frac12CV^2$), and dynamic exponential RC charging curve
Capacitor Application Presets
RC Exponential Transient Response Curve (V_C vs Time)
Time Constant τ = R · C = 1000 ms1τ (63.2%)15.8 V1000 ms
2τ (86.5%)21.63 V2000 ms
3τ (95.0%)23.75 V3000 ms
4τ (98.2%)24.55 V4000 ms
5τ (99.3%)24.82 V5000 ms
Stored Charge (Q)
2500 μC
Q = C × VStored Energy (E)
31.25 mJ
E = ½ C V²5τ Full Steady-State
5000 ms
99.3% ChargedWhat is a Capacitor?
A capacitor is an electronic component that stores electrical energy in an electrostatic field created between two conductive plates separated by a dielectric insulator.
Formula & Step-by-Step Calculation
Q = C · V, E = ½ · C · V², τ = R · C
Charge, stored electrostatic energy, and exponential charging time constant.
Worked Step-by-Step Examples
Example 1
A 100μF capacitor is charged to 25V through a 10kΩ resistor
Solution: Charge: 2,500 μC, Energy: 31.25 mJ, τ = 1,000 ms (1.0 s)
• Q = 100μF × 25V = 2,500 μC; E = 0.5 × 100e-6 × 625 = 0.03125 J; τ = 10,000 × 100e-6 = 1.0 s
Common Real-World & Academic Use Cases
- ✓ Power supply smoothing filter design
- ✓ 555 timer oscillator frequency tuning
- ✓ Camera strobe flash discharge energy sizing
How to Use the Capacitor Calculator (Energy & RC Time Constant)
1
Input Capacitance & Voltage
Specify capacitance (μF) and charging voltage (V).
2
Input Resistor
Enter charging resistance to determine time constant τ.
Frequently Asked Questions
Q: What is the significance of one time constant τ?
After 1τ, a charging capacitor reaches 63.2% of its maximum voltage; after 5τ, it is considered 99.3% fully charged.