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# Energy stored on a capacitor Tweet

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1. Energy stored on a capacitor
Hi, does anyone know a detailed experiment on proving E= 0.5CV^2

I've read about discharging a capacitor through combinations of light bulbs with an constant total resistance but I don't understand how that would prove the equation

Thanks
2. Re: Energy stored on a capacitor
Well the energy used by a lightbulb would be a Ws (Watt second). Basically, however long the bulb is switched on for in seconds is its energy in Joules. And the power in Watts is voltage x current (P=VI). Power is also v^2/r, so you could use the constant resistor value for that.

So you could charge a capacitor, and make it power a light through a resistor. An LED might be better, as bulbs will get gradually dimmer and dimmer (changing their resistance, etc). But an LED will be a lot cooler and at around 0.6V it will turn off, so you know where it starts and where it ends.

So the equation linking the two would be something like:

Pt = 0.5CV^2

Where Pt = (v^2/r).t