Electromagnetism
Capacitor Calculator
Solve Q = CV for charge, capacitance or voltage. Also calculates energy stored E = ½CV².
Result
Q = CV
Energy Stored (½CV²)
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J
Step-by-Step Solution
What is a Capacitor?
A capacitor is an electrical component that stores energy in an electric field between two conducting plates separated by an insulating material (dielectric). Capacitors are fundamental in electronics — they smooth power supplies, filter signals, store energy in camera flashes, and enable touchscreens.
Q = CV | E = ½CV²
Q = charge (C) | C = capacitance (F) | V = voltage (V) | E = stored energy (J)
💡 The energy stored in a capacitor is E = ½CV². This is why capacitors in camera flashes can deliver a very brief but intensely bright burst — all the stored energy discharges in milliseconds.
Real-World Applications
Camera Flash
A large capacitor charges slowly over a few seconds, then discharges in milliseconds to power the flash tube.
Electronics Filters
Capacitors block DC and pass AC. They smooth rippling voltages in power supplies and remove noise in audio.
Touchscreens
Capacitive touchscreens sense the change in capacitance when a conducting finger approaches the screen.
Supercapacitors
Supercapacitors (up to 3,000 F) bridge the gap between batteries and capacitors for energy storage applications.
Frequently Asked Questions
What is the Farad?
The Farad (F) is an extremely large unit. 1 F = 1 Coulomb per Volt. Most practical capacitors are measured in microfarads (μF = 10⁻⁶ F), nanofarads (nF = 10⁻⁹ F), or picofarads (pF = 10⁻¹² F). Supercapacitors can reach thousands of Farads.
How do capacitors store energy?
When voltage is applied, opposite charges build up on the two plates, creating an electric field in the dielectric. The energy is stored in this electric field: E = ½CV². When discharged, the field collapses and drives current through the circuit.
What is the difference between capacitors in series and parallel?
In parallel: C_total = C1 + C2 + ... (capacitances add, like resistors in series). In series: 1/C_total = 1/C1 + 1/C2 + ... (capacitances add reciprocally, like resistors in parallel). This is opposite to resistors!