Capacitor Calculator

Understanding Capacitors

A capacitor is a fundamental electronic component that stores electrical energy in an electric field between two conducting plates separated by an insulating material (dielectric). The capacitance C = Q/V defines the ratio of charge stored (Q) to voltage applied (V), measured in farads (F). The energy stored is E = ½CV², which depends on both capacitance and voltage. Capacitors are found in virtually every electronic device, from smartphone circuits to industrial power systems.

This calculator handles three modes: single capacitor calculations (find capacitance, voltage, charge, or energy from two known values), series combinations (where total capacitance decreases), and parallel combinations (where total capacitance increases). Enter values in farads; results are shown in both farads and microfarads for convenience.

Series and Parallel Capacitor Combinations

In a series connection, capacitors share the same charge but divide the voltage: 1/C_total = 1/C₁ + 1/C₂ + ... The total capacitance is always less than the smallest individual capacitor. In a parallel connection, capacitors share the same voltage but store charge independently: C_total = C₁ + C₂ + ... The total capacitance is the sum of all individual values. This is opposite to how resistors combine: resistors add in series, while capacitors add in parallel.

Energy Storage

The energy E = ½CV² stored in a capacitor increases with the square of voltage, making voltage the dominant factor. Doubling the voltage quadruples the stored energy. Supercapacitors (ultracapacitors) achieve very high capacitance (hundreds to thousands of farads) and are used in regenerative braking systems, backup power, and energy harvesting. While they store less energy per unit mass than batteries, they can charge and discharge in seconds and survive millions of cycles.

Practical Applications

Capacitors serve many roles in electronics: filtering (smoothing rectified AC to DC in power supplies), timing (RC time constant circuits in oscillators and timers), coupling/decoupling (passing AC signals while blocking DC between amplifier stages), energy storage (camera flash units, defibrillators), and power factor correction (improving efficiency in industrial AC systems). Choosing the right capacitor involves balancing capacitance, voltage rating, size, cost, and frequency response.

Frequently Asked Questions

What is capacitance?

Capacitance C = Q/V is the ability to store charge per unit voltage, measured in farads. Practical values are typically microfarads or picofarads.

How do series and parallel capacitors differ?

Series: 1/Ct = sum of 1/Ci, total is less than smallest. Parallel: Ct = sum of Ci, total is the sum. Opposite of resistor behavior.

How much energy does a capacitor store?

E = ½CV². Energy scales with voltage squared. A 1000µF capacitor at 50V stores 1.25 joules.

What are common capacitor applications?

Power supply filtering, timing circuits, signal coupling, energy storage (camera flash, defibrillators), and power factor correction.

How do capacitors differ from batteries?

Capacitors store energy in electric fields (fast charge/discharge, low energy density). Batteries store energy chemically (slow, high energy density). Supercapacitors bridge the gap.