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Electronics and Physics Suite

Capacitor Calculator

Calculate capacitance, electric charge, voltage, or stored energy. Select the two variables you know to solve the remaining ones instantly.

1. Select Your Known Variables

Capacitor Physics and Formulas

Capacitors are fundamental building blocks in electronics, acting as voltage reservoirs or high-pass frequency filters. Understanding how charge and energy scale with potential difference is critical for sizing decoupling, filtering, or power delivery components.

The Capacitor Formulas

The two core equations describing capacitance metrics are the charge distribution formula and the integration of energy:

Charge Equation
Q = C × V
Stored Energy Equation
E = 0.5 × C × V²

Equations for alternate variables:

Solving for Voltage (V)
  • From Charge and Capacitance: V = Q / C
  • From Energy and Capacitance: V = √(2E / C)
  • From Energy and Charge: V = 2E / Q
Solving for Capacitance (C)
  • From Charge and Voltage: C = Q / V
  • From Energy and Voltage: C = 2E / V²
  • From Energy and Charge: C = Q² / 2E
Solving for Charge (Q)
  • From Capacitance and Voltage: Q = C × V
  • From Energy and Voltage: Q = 2E / V
  • From Energy and Capacitance: Q = √(2E × C)
Solving for Energy (E)
  • From Capacitance and Voltage: E = 0.5 × C × V²
  • From Charge and Voltage: E = 0.5 × Q × V
  • From Charge and Capacitance: E = 0.5 × Q² / C

Common Questions and Physics Insights

What does a capacitor do in an electrical circuit?

A capacitor is a passive electronic component that stores electrical energy in an electric field. It acts like a tiny temporary battery: it blocks direct current (DC) while allowing alternating current (AC) to pass, filters out voltage fluctuations in power supplies, and releases energy rapidly when needed.

What is the relationship between charge, voltage, and capacitance?

The relationship is defined by the formula Q = C × V, where Q is the charge in Coulombs, C is the capacitance in Farads, and V is the electrical potential in Volts. This means a capacitor with a higher capacitance can store more charge at the same voltage level.

How is energy stored in a capacitor calculated?

The electrical energy E (measured in Joules) stored in a capacitor is proportional to both its capacitance and the square of its voltage. The formula is E = 0.5 × C × V². You can also compute it using charge and voltage: E = 0.5 × Q × V.

What is the significance of the dielectric material?

The dielectric is an insulating layer (like ceramic, mica, paper, or plastic) between the capacitor plates. It prevents the charges from flowing between the plates and increases the capacitance by reducing the strength of the electric field, allowing more charge to be stored at a given voltage.

What happens when capacitors are connected in series vs. parallel?

Connecting capacitors in parallel increases the total capacitance (C_total = C₁ + C₂ + ...), because it increases the effective plate area. Connecting them in series reduces the total capacitance (1/C_total = 1/C₁ + 1/C₂ + ...), because it increases the distance between the outermost plates.

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