Sea is a good conductor of electricity

[quietrain]

hi , i was just wondering, if the sea is a good conductor of electricity, when thunder should strike it, won't electricity be conducted everywhere and everything dies in the sea?

how far does electricity spread out? is there some sort of limiting factor? thanks!

 

[K^2]

The total current through water is the same as through lightning, which is a ridiculously high amount of current, but the current density drops the further you get from the point where lightning actually hit. That means the current flowing through a body is going to drop very rapidly with distance from that point. Unless you happen to be right next to it, you are fairly safe.

If you happen to be swimming, you are far safer in salt water than in fresh water. In fresh water, you are a much better conductor than water, and so you'd be the conduit of choice for lightning. In salt water, there is very little difference, so your odds of getting hit aren't particularly high.

 

[quietrain]

i see.. what if someone puts a never ending source of live wire in the sea, does it mean that it will keep spreading ? or the current density will put a limit to the distance? is there some equation or law governing this ?

 

[DaveC426913]

i see.. what if someone puts a never ending source of live wire in the sea, does it mean that it will keep spreading ? or the current density will put a limit to the distance? is there some equation or law governing this ?

Well, that the same as a groundwire. We do this all the time. Earth is effectively an infinite sink for charge.

 

[Adjuster]

Clearly lightning can kill creatures in water if it strikes close enough, but over history there must have been many lightning strikes without all sea life being eliminated. Clearly there is a safe distance beyond which the current density is too low to matter, can anyone suggest how far that might be?

I've seen some contradictory ideas about how lightning currents may spread out in water, but the most common suggestion seems to be that it approximates to a hemisphere - at least away from the immediate area of the strike (how far away?). Does anyone out there have reliable information on what really happens? For that matter, how much current density would be lethal - I might guess 0.1A per square metre??

 

[quietrain]

nature sure is weird.

i have seened a video of an electric eel discharging when a croc bit it. and only the croc got shocked but the fishes around the eel was still swimming.

i mean, shouldn't the whole water get electrocuted?

also, electric charges don't just die out right? shouldn't they be spreading and keep traveling throughout the whole sea?

if grounding comes into play, then how do we know if i were to put a live wire into the sea, will it be grounded straight away or will it spread and then get groundeD?