Kondensator-Rechner

A capacitor is a device that stores electrical energy. This calculator computes charge (Q), energy (E), capacitive reactance (Xc), and RC time constant based on capacitance and voltage.

Key Formulas

• Charge: Q = C × V (Coulombs)
• Energy: E = 0.5 × C × V² (Joules)
• Reactance (AC): Xc = 1 / (2πfC) (Ohms)
• RC Time Constant: τ = R × C (seconds)

Parameters

• Capacitance: Stored charge per unit voltage (Farads). Common units: μF (1e-6 F), nF (1e-9 F), pF (1e-12 F)
• Voltage: Potential difference across capacitor (Volts)
• Frequency: AC frequency in Hz. Use 0 for DC.

How It Works

1. Enter capacitance in Farads (use scientific notation or prefixes)
2. Enter voltage applied to capacitor
3. Optionally enter AC frequency (leave 0 for DC)
4. Review charge, energy, reactance, and time constant

Common Values

• Electrolytic: 1–100 μF (high capacitance, polarized)
• Ceramic: 100 pF–100 μF (temperature-stable)
• Film: 100 nF–100 μF (precise, low loss)

Applications

• Power supplies: Filter ripple voltage
• Timing circuits: RC time constant determines frequency
• AC coupling: Block DC while passing AC
• Energy storage: Flash photography, power backup
• Impedance matching: AC networks

FAQ

Q: What does charge on a capacitor mean? A: Charge is the amount of electrical energy stored. A 1 μF capacitor at 10 V stores 10 μC (microcoulombs) of charge.

Q: Why does energy increase with voltage? A: Energy is proportional to V². Doubling voltage quadruples energy storage.

Q: What is capacitive reactance? A: Reactance (Xc) is the “resistance” a capacitor presents to AC. Higher frequency → lower reactance → easier AC passes.

Q: What is RC time constant? A: τ = R × C is the time for a capacitor to charge to 63% through a resistor R. Used in oscillators, timers, filters.

Q: Why use DC = 0 Hz? A: Capacitors block DC (infinite reactance at f=0). Set frequency to 0 to skip reactance calculation.