Capacitor Energy Calculator

A capacitor stores electrical energy in an electrostatic field created between two conductive plates separated by an insulating dielectric material. The primary governing equation for the energy stored in a capacitor is E = 0.5 * C * V^2, where E represents energy in joules (J), C is the capacitance in farads (F), and V is the voltage across the capacitor in volts (V). Alternatively, since charge (Q) equals capacitance times voltage (Q = C * V), the stored energy can also be expressed using charge and voltage as E = 0.5 * Q * V, or using charge and capacitance as E = Q^2 / (2 * C).

Let us calculate the energy stored in a capacitor with a capacitance (C) of 100 microfarads (100 uF or 0.0001 F) connected across a 12-volt (V) direct current power supply. First, substitute the values into the primary formula: E = 0.5 * C * V^2. Square the voltage: 12^2 = 144. Next, multiply by the capacitance: 0.0001 * 144 = 0.0144. Finally, multiply by 0.5 to find the total energy: 0.5 * 0.0144 = 0.0072 joules, or 7.2 millijoules (mJ) of stored electrical energy.

Always convert your metric prefixes into base units before performing calculations—such as converting microfarads (uF) to farads by multiplying by 10^-6. Exercise extreme caution when handling large capacitors, as they can retain dangerous amounts of electrical charge long after the power circuit has been switched off. Always verify the maximum voltage rating (working voltage) of your capacitor to prevent dielectric breakdown and catastrophic component failure.