In short: I = V / R (This is the original formula.) It establishes a reversed relationship between Resisance (R) and Current or Amperage (I), which can also be understood as a kind of traffic flow of electrons (negatively charged particles.) Current is said to be stronger if more charges pass through the same section of a conducting agent -- like a copper wire in the cable. V is Voltage in the formula.

But lately, we speak of another formula too. One which establishes relationship between power (W) and voltage (V.) It goes like this:

I = W / V; where I = (W / R)2

What is important from this relationship, is that as a rule a low voltage light draws higher amperage for the same brightness (measured with 'W' ) unless resistance is less by a power of two (or a square root.) But that rarely happens, here's WHY:

To operate from the mains low voltage lights need a transformer (adaptor in techno speak), which has a coil in it to work. Current passing through that coil meets high resistance (you hear the typical low humming of a transformer), and quite of a lot of the power (W) generated turns into heat. The rest powers your low voltage outlet.

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