What are the physiological results of being hit by lightning? I guess this can be extended to other kinds of strong but short electric shock.

Does the path of the lightning get "cooked"? What is this path, nerves (they are our own electricity conductors after all) or something else? What parts of the body usually get damaged, and by what mechanism? What is the usual long-term outcome (someone said that death is rather rare)?

1 Answer 1


H = IxIxR

Where H is the amount of heat produced when a current of I is flown through a conductor of resistance R.

The resistance of human body may be as high as 100,000 ohms. An average bolt produces current of 30kA. If a typical lightning were to pass completely through a human body (even though this is not the case), the heat energy liberated will be 9X10^14 J which is HUGE. The human body is mostly made of protein, with water, fats, and nucleic acids for the most part. Protein coagulates and water evaporates as the temperature rises, and if it is too high the whole thing oxidises, and what will be left will unoxidisable ash and unburnt carbon.

In short, yes it is the heat injury in lightning. But in electrocution, there can be other causes such as cardiac arrhythmia, because the amount of voltage need not necessarily be high enough to oxidise everything up.

  • Correction: it should be 9 x 10^14 Watts, not Joules. Also it should be power, not heat. Heat = (heating) Power x Time. A discharge may last as little as 1 microsecond, meaning the amount of energy would be much less, about 9 x 10^8 J. This is still enough to elevate 100kg of water by about 2000K (more than enough to vaporize it). The conclusion is that not all current must go through the body of survivors, or it must be lower current events.
    – Real
    Nov 5, 2021 at 19:18

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