My difibrilator hit me at 31 joules,?

Question

Can that be translated into volt and amps....I can' really understand joules......Also , my defibrilator is internal so it functions more efficiently than external....I've had both.

Answer 1

An external defibrillator seems to work around 4000V. The voltage is necessary because in order to achieve defibrillation, something like 1A has to pass through the chest. Given the size of the electrodes the skin/bone/muscle have a resistance of a couple of kOhm, so the device needs to put out a lot of voltage. The energy in the pulse is pulse current times pulse voltage times pulse length (you really need to integrate over the pulse waveform but I omit that part for simplicity), so an external machine which puts on the order of 4kW power into a patient has to have a pulse length of 1/40th of a second to get to the 100J or so pulse energy that are being used.

An internal device can be scaled down in voltage and current (and energy) because there is no need to go through the skin and the bones. This seems to be done with voltages around 1000V:

http://en.wikipedia.org/wiki/Defibrillation

Answer 2

31 joules is an energy. It is delivered by a combination of volts and amps, but the overall effect (in this case) is the result of multiplying volts x amps x seconds, which gives the energy in joules.