text: #3  Joule is a electrical term for 1 watt-second. So it is a power rating.\nOne joule is also: The work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt, with the symbol C·V.\n\nAs for why they use it, I think it is a small enough meaurement that 360 joules is much better than 0.1 Kilowatt Hours\n\n2. Varies. There are a few different waveforms that are used by different manufacturers. Each one is based on different resistances.  Honestly, If the Defib is being used for its intended purpose, it should not matter.  This is because either it is a biphasic (newer model) and using the resistance to figure out proper power or Monophasic and usually will increase in power with each shock (most of the times will max out at 3rd shock of 360 joules)  They figure that the resistance is between 25 and 200 ohms with biphasics shocking the equal to 360 joules at 50 ohms (per Medtronic lifepak 500 stat sheet)\n\n1. Again Varies depending on model (this causes part of the wave form in addition to the length of dischage time) But the current overall will change with change in joules.