# How many volts is 3 watts?

If you know the resistance of your load you can determine the voltage that would be necessary to dissipate 3 watts.

Power law tells us watts=voltage * current Ohm's law tells us voltage=current * resistance

Sub "watts/voltage" from power law for "current" in Ohm's law and we have

voltage=watts*resistance/voltage

Multply both sides by voltage to get them on one side:

voltage^2=watts*resistance

Take the square root of both sides (too hard to do the radical in ascii):

voltage=sqrt (watts*resistance)

So, if you know how resistive your load you can now calculate the necessary voltage to dissipate 3 watts.

Well if your plugged into a house hold outlet and in the US your pulling ~120volts. The whole US runs off of 120volts. There are a few devices that run off a 240 volt setup in the US (things the generate heat) but they really run off 2 - 120 volt lines. But with 3 watts your not using one of those :P.

If your working of a battery system, well it depends on the battery.