Water and electricity spells - RL physics approach

Question

I like to master (and play) in a world I can believe (even fantastic ones). This question comes from D&D3.5 but applies to every game where reality collides with things you can't (usually) do. So I wanted to come up with an answer to this question guided by real world physics and how it works in reality...

What happens to all creatures underwater when you cast an electricity spell?

I know we have to draw a line somewhere between reality and a game, but I would encourage cunning from players to use their capabilities and skills while that does not get the game broken.

It depends... distilled, deionized, or natural water? ^_^ Jokes apart, the only advice that I could give you is that in mineral water electricity tends to dissipate uniformly in a spherical shape (or hemispherical, if the current initiates from above the water surface). It usually covers a greater volume than on air (which has a much higher impedence) but travels a shorter distance because it dissipates in any direction. That said, one could rule, for example, that a classical thunderbolt spell could assume a "ball" shape underwater. — Erik Burigo, Jul 22 '11 at 18:07
Kind of but no, on that link talks about spells on specifically D&D3.5... And c'mon Fire? I could believe a ball that can remain on fire underwater, imagining boiling water around it, think of lava underwater... But Lightning? its like when you say this movie sucks at the cinema when you cant seem to accept that given a certain paradigma, one guy does something that isn't possible... (ok, it's a movie but some people like me tend to get annoyed a bit by this). — apacay, Jul 22 '11 at 19:20
Check out this Q on physics.se: http://physics.stackexchange.com/questions/917/lightning-strikes-the-ocean-im-swimming-in-what-happens — RMorrisey, Jul 22 '11 at 23:25
@apacay For what its worth certain things will continue to burn under water, such as white phosophorous. — TimothyAWiseman, May 29 '12 at 22:56
I have a solution, but it only works for frictionless water in a sphere ;) — Dakeyras, Jan 14 '13 at 16:34

score 7 · Accepted Answer · answered Jul 22 '11 at 18:12

Caution: I am not a physicist, nor do I play one on the Internet.

I did a quick Google search and came across this little gem: http://wiki.answers.com/Q/If_lightning_strikes_the_ocean_while_you_are_in_it_how_close_does_the_strike_have_to_be_for_you_to_feel_it

There are several factors in play here: the salinity of the water, the distance of the creature from the point of impact, and the voltage and current of the electricity being applied.

Also, is this being done for combat purposes? (someone using water for cover), or as a skill (someone using lightning to, say, fish or what-not)? Those would likely be different scenarios for rules.

I'm more of a fan of abstracting away the physics of the strike, and instead let chance and GM fiat take charge. (ie: You cast lightning against the water to attack the mer-men, but since you rolled low, they're already on the other side of the lake when it hits).

Hope this helps!

It is useful indeed. You mean then that the spell conjurer should not be underwater when he casts it, and on an ocean it's probable you wouldn't feel nothing. But, what if its a not wide ocean. The consequenses for a room with water and a lightning spell? — apacay, Jul 22 '11 at 18:28
Unless the caster has some immunity to electricity, I wouldn't want to be them if they unleashed a lightning ball underwater. If it's a room with water, again it depends on the mineral content of the water. A purified spring with no mineral content (magical water) might not have any effect at all, whereas a pool in a cave would have lots of dissolved minerals. And again, it would depend on the charge that the magic user would deal out and the position of the recipient. — , Jul 22 '11 at 18:43

score 5 · Answer 2 · edited Apr 13 '17 at 12:39

Things like this come up constantly in my Shadowrun games. As a GM, I try to follow these rules:

Allow it if it makes the game more fun/exciting. Improvise for dramatic effect.
Don't make the rules more complicated than they already are.
Don't let the players spend an hour arguing about it. Your job as the GM is to politely say, "This is how we're going to handle it," adjudicate the result, and keep the game moving.

Based on this Q...

https://physics.stackexchange.com/questions/917/lightning-strikes-the-ocean-im-swimming-in-what-happens

...it seems like lightning should have a ball effect (as someone mentioned) like a fireball, doing normal damage on the surface in fresh water, and maybe having a reduced radius in salt water but penetrating underneath the surface.

Water and electricity spells - RL physics approach

2 Answers2