Real Capacitor Model

How to Use

• Cap slider — change capacitance (1–100 µF).
• ESR slider — adjust equivalent series resistance (1–1000 mΩ).
• ESL slider — adjust equivalent series inductance (1–100 nH).
• Hover over the impedance plot to read exact values at any frequency.

What to Observe

• The ideal capacitor (blue) falls as a straight line: \(|Z| = 1/\omega C\).
• The real capacitor (red) has a V-shape — it reaches a minimum at the self-resonant frequency (SRF).
• Below SRF: capacitive (impedance decreases with frequency).
• Above SRF: inductive — the capacitor acts like an inductor!
• ESR sets the impedance floor at resonance.

Key Equations

\[f_{SRF} = \frac{1}{2\pi\sqrt{ESL \cdot C}}\]

\[|Z| = \sqrt{ESR^2 + \left(\omega \cdot ESL - \frac{1}{\omega C}\right)^2}\]