## Voltage VS Amps

This may have been answered before, but I have searched. Throughout all my reading of High Voltage devices, I have noticed that some have high amps and some don't. For instance a Van De Graff generator creates very nice HV but little amps.
Well, to be to the point, my question is: What determines a charge having a large amount of amps or not?

active| newest | oldestExample; 100 watt light bulb / 110 volts = .91 amps. Nice!

But if I use the 12v; 100watt light / 12v = 8.3 amps.

I'm believing I would be drawing 8.3 amps from the battery to power this light.

Plus the converter draw...

Please tell me which is correct?

Your figures illustrate quite nicely the reciprocal relationship between volts and amps. For the same amount of power, insert a smaller voltage figure, and the amperage rises, and vice-versa.

For most devices, using a higher voltage also drives more current through. For this example, however, we'll say the bulbs are appropriate -- there are certainly 100W 12V lights, so we'll assume the bulbs in each equation are correctly voltage-rated (the light bulbs were 12V and 110V, respectively.)

So, both examples are correct. In each case the overall power consumption is the same.

But you're probably wondering about battery capacity, right? The 12V example will be

closestto the estimated draw on the batteries. As you know, that doesn't include the power required to run the inverter...the 12V calculation assumes a "lossless" conversion.(ever thought about using 12V lights?)

The reason I say "is a slight lie" is that actually current, not voltage, defines a Van De Graaf generator and similar electrostatic devices- they are actually a class called "constant current source". In this case, the voltage reached by the charge is the voltage at which the leakage current to the air is equal to the supply current. If a lower-resistance circuit is provided the dome voltage will drop accordingly.

Current * voltage is also limited by power- a VDG using 50 watts clearly won't be able to provide a high current at 100,000V, but a high-powered NST or flyback at several hundred watts will provide more current. Also note that a lot of AC high voltage sources (like ignition coils) supply intermittent current rather than constant, which increases the instantaneous current that can be supplied from a constant power consumption (rather like the millions of amps that flow for a tiny fraction of a second in a lightning strike from a much smaller constant charge build up)

I hope this answers some of your questions- you will find most of the answers you are looking for in a physics textbook, this is just a very brief summary.