# Electronic – Capacitors and capacitance

capacitancecapacitor

this time I'd like to ask a few questions about capacitors, all noob questions again;

• What's a better idea, having one capacitor at 5x farads or five capacitors at x farads each? I want to get a certain amount of voltage and want to discharge the direct current as fast as possible.
• I'm trying to build an amateur railgun, and intend to shoot projectiles that weigh about 10 grams. Using the formula that someone helped me with in my other question, in order to give that a speed of 100m/s at a total of 20.000 uF assuming 2% efficiency I'd need a little less than 112V's. The question is, is this amount of voltage I need my capacitor or series of capacitors to provide for the duration of the shooting?
• What determines how much voltage a capacitor can hold? This may come off stupid as I am aware that there is a voltage rating when you buy them, but better safe than sorry.
• I was only assuming 2% efficiency, and depending on my rail length it could be higher. The question is, what determines how fast the capacitor will discharge and how it can be prevented from going above the rated voltage?