Step 4: Amps
But wait, since voltage is “electrical pressure” then there must be a measurement of volume, shouldn’t there? Well there is, and the measure is called the Ampere (A). The ampere, or amp, is the volume of electrons that are flowing (current). The unit is equivalent to about 6,242,000,000,000,000,000 (an assload) electrons flowing past a point in one second. Different electrical appliances require different amperages, with the typical LED flashlight requiring 60 milliamps (0.06A), an iPod requiring about 400mA and a refrigerator requiring 10A. With more current more work can be done, since more electrons carry more energy than fewer electrons. As can be seen by this video of a roofing nail burning, when large currents flow quite a lot of "work" can be done.