Volts (Pressure), Amps (Gas), and Resistence (Loads)

Volts is the pressure in the tank, Amps is the actual gas (also volume), and Ohm (resistance) is loads, including the diameter and length of the "tubing" (wire), and resisters along the way (loads, like lights, motors, radios, etc).

Ohm's Law.   Voltage = Amps x Resistence (V = I x R)